Using Transfer as a Schema to Learn about Energy: A Modular Approach

Author: Matthew N VanKouwenberg

School/Organization:

The U School Philadelphia

Year: 2021

Seminar: Renewable Energy Schemes

Grade Level: 10

Keywords: Constructivist, electricity, Electromagnetic Spectrum, Energy Transfer, Environmental Science, Eolic, Experiment, Generator, global warming, High School, Lab, Magnetism, Mechanical Energy, Middle School, Motor, PhotoVoltaics, Physical Science, physics, student-centered, Thermodynamics, wind energy

School Subject(s): Science

This unit is designed to help create a student-centered classroom where through their experiences, students construct meaning around energy and our environment. There are many activities intended for middle or high school students. While intended to be a complete experience, it is designed so that individual modules can be taken and used as your time and the structure of your class allows. There are discussions of activities related to mechanical energy, magnetic energy, photovoltaic energy and others and connecting them to global warming with thoughts about how we can transform our energy production to help reduce the impacts of global warming.

1 Star2 Stars3 Stars4 Stars5 Stars (No Ratings Yet)
Loading...

Full Unit Text
Content Objectives

Many people today do not think about the consequences of their actions, this unit attempts to help people see the impacts of their actions and help them realize their agency in helping benefit our world. We will look at energy, energy production and how we use energy to develop a sense of urgency and agency in changing our world in a constructivist manner which will help us understand big ideas instead of simply memorizing facts.

The purpose of this unit is to help students internalize ideas related to energy, energy production, and its impact on the environment. This will be approached in a constructivist manner to give the students the best chance of internalizing the information and transferring the ideas into their lives and future decisions. This is intended as a modular introductory unit, one that touches on many topics, but does not complete the study of them. It will contain many modules which work better as a whole, but can be broken into discrete modules. If only certain modules are taught, many of the larger ideas and the transfer of concepts may be lost, but your constraints may require this approach. Through the use of this unit, future units in the course will gain context and speed up the acquisition of and internalization of knowledge to help students learn specifics while seeing the interconnected nature of the universe, our world, and our actions and their impacts.

As most people now understand, our environment is changing rapidly and not in a way that is good for humanity. The primary stressors on the environment are greenhouse gases that are mostly generated by the production and use of energy. Most people intellectually understand that burning fossil fuels, be it for electricity production or direct use such as transportation, is bad for the environment, but for some reason don’t connect their individual actions, societal actions, nor corporate actions to the effects. People realize burning fossil fuels generates greenhouse gases and that greenhouse gases lead to climate change, but somehow don’t connect that burning fossil fuels has a causal relationship with climate change. Maybe on an intellectual level people could be drawn to state the relationship; AàB and BàC therefore AàC, but our actions belie the understanding of that causal relationship. By the end of this unit students will have drawn direct connections between the actions people take and the consequences, including unintended consequences, and hopefully through these exercises internalize the meaning of this and transfer their academic understandings into productive, or at least non-destructive, actions.

Energy

Energy is the capacity to do work. That is the fundamental understanding that is the basis of this unit. The second key understanding is that energy is neither created nor destroyed, it is just transferred from one kind to another. We use energy by transferring it from one kind to another to accomplish the tasks we want, be it moving around in a car or cooking food or lighting a lightbulb.

The main source of energy in our solar is the sun. Some people may ask about hydro or eolic (wind) energy, but both of those are driven by the sun as the temperature differences drive wind and the energy from the sun drives the water cycle. Nuclear, geothermal and things like tidal energy are present on Earth, but at orders of magnitude so small compared to the sun that they ultimately are barely consequential. As such solar energy and its derivatives will be the focus of this unit, not nuclear nor geothermal.

One example of energy being the capacity to do work with which many students may be familiar is using the energy from the force of gravity to drive many processes. In class you may have demonstrated dropping a ball or other things to accomplish a task. Many Rube Goldberg Machines use gravity as a means to accomplish many tasks, be it flipping a switch or turning on a toaster. Skateboards going down a ramp is also a very common example of using energy to accomplish something, in this case movement. The force of gravity is calculated by the equation:

  • G=gravitational constant
  • =mass of object 1 (often the Earth or Sun )
  • =mass of the object 2

There are many forms of energy that may be useful to explore, but it may be useful to categorize them into potential energies, energies that are stored, and direct energies, energies that are used right away. Examples of potential energies include: gravitational potential (GPE), chemical potential (ChE), elastic potential (ElE), magnetic potential energy (MagE), and nuclear potential(NPE). Energies that are used right away include: thermal (ThE), audio, kinetic (KE), radiant (solar), light (photo), and electrical (EE). Each of these forms of energy are generated in different ways that will be explored later in the unit, but we should be familiar with them as different forms of energy from the start.

Energy Transfer

Energy transfer is very important to understand as it is basically how we do everything. Even thinking is the transfer of chemical energy into electrical energy in our brains. We may be tempted to start with the force of gravity, but for introductory purposes I would suggest using energy transfer as students more easily recognize their experiences with this. The formula for GPE is:

  • m=mass object
  • g=force of gravity on Earth (9.8
  • h=distance from starting point to the ground state

The formula for KE is:

  • m=mass of object
  • v=velocity of object

It is useful to consider that since energy is neither created nor destroyed, as an object falls the GPE is simply converted into KE (minus ‘vampire’ effects like friction which, at this level are normally glossed over).

A basketball or tennis ball or superball bouncing shows us GPE transferring into KE, then into ElE, then back into KE and GPE as the cycle restarts.

As mentioned above we must be aware of ‘vampire’ effects, these are types of energies that are unintended transfers such as the heat of an engine in a car. We burn oil in cars for KE, so the ThE is effectively wasted energy, colloquially called ‘vampire’ energy. We must be aware of these effects both as we think about the impacts of energy and as we think about what people observe during labs and demonstrations. We must know these things from the beginning as educators, but it is recommended to introduce them a little later for students.

Once students internalize that the energy isn’t consumed and is simply transferred we can move onto other energy transfers more in line with the emphasis of the unit. Most energy we use comes from chemical energy, be it energy from food to fuel our bodies or fossil fuels to fuel our transportation and power plants. What people often don’t consider, but makes sense in retrospect, is that not all of the energy transfers into the form we want. An example with which students may be familiar, even in areas where most students don’t have access to vehicles is a lit lightbulb. LED lightbulbs are four to ten times more efficient than incandescent lightbulbs, but they are nowhere near 100 percent efficient. A lightbulb that has been on for a long time is rather uncomfortable to change, this is because it is hot. In most cases we do not intend lightbulbs as a source of heat, but as a source of light. This means that the heat given off by the lightbulbs is a form of energy that is wasted, and not useful.

It is important to realize that most of the energy we directly use starts out as ChE and transfers into ThE. This happens through entropy and also our direct action. For example the energy that fuels our bodies is primarily from the carbon bonds (ChE) in our food and transferred through the Krebs Cycle into usable energy (adenosine triphosphate, ATP) that our bodies combust to do everything from thinking to running. That ChE comes from the things we eat which, through the food web, work their way from producers which get their energies from the sun. The specifics of photosynthesis and respiration are for another unit, but they do present opportunities for multi and interdisciplinary projects.

Our ability to run comes from the food we eat (ChE), which even if we are carnivores comes from plants which, through photosynthesis, convert radiant energy into ChE. While we run we also generate heat and audio energy.

Referring back to the lightbulb, they give off light and heat, this energy comes from electricity which usually comes from spinning magnetics (MagE) which usually move from steam from water boiling from the burning of fossil fuels. The fossil fuels are formed from plants and animals through geologic processes over millennia, so ultimately come from the sun. The full process could be described as:

solaràChEàThEàMagEàEEàphoto and ThE

Work

At this point it makes sense to introduce the concept of work. It has already been discussed, but not by name. Work is basically how much we move things. The thermal energy in the last example spinning the magnets is an example of work. Work is defined as:

  • W=work
  • F=force
  • s=displacement, the distance moved.

The ThE from the ChE spins magnets and wires relative to each other. This spinning moves electrons which we call electricity.

In an earlier example a skateboard went down a ramp, this is work as gravity pulled the skateboard down.

Introductory Thermodynamics

Thermodynamics is important to understand because it is the study of how heat interacts with other forms of energy. This includes how we generate most of our electricity as well as how vehicles operate and many other things. A deep study of this may not be appropriate for all groups, but some of the basics of it are things we all experience and it is really just a matter of reframing how we think about everyday occurrences.

The first law of thermodynamics states that energy can neither be created nor destroyed within a system. Basically, when energy is used, it simply transfers from one type of energy into another. When we burn ChE in natural gas it turns into ThE that can be used to boil water or cook food or many other uses. The energy from the flame did not disappear, it moved into the water.

The second law of thermodynamics basically states that heat goes from hot objects to cold objects, so if you hold ice in your hand the cold from the ice is not going into your hand, it is the heat from your hand going into the ice. The absence of that heat is why you feel cold. From an observational point of view it is a subtle distinction, however without this distinction engines would not be able to function in addition to many other machines not working. This concept may be difficult to imagine without a lot of guidance, but if anyone has used a potholder to take something out of the oven we can tell that the heat from what was in the oven is going into the potholder and our hands, it is not ‘cold’ from our hands going into what was in the oven.

The third law of thermodynamics essentially states that things go from more ordered to less ordered. So for example chemical energy is very ordered, we can isolate and use that energy, but as chemical energy is released, heat and light and often sound are given off. Those are less orderly forms of energy that are more difficult to use. This is called entropy and the entropy of systems increases. A visual to help with this understanding is putting a drop of food coloring into a glass of water. A drop of food coloring as a drop has all of the food coloring in one spot, very orderly, but as it drifts throughout the water it distributes like clothes from a drawer onto the floor and throughout a bedroom.

Why is all of this important? Well it helps us understand the inefficiencies of our systems. We can be impressed by the amount of energy in a gallon of gasoline, however the average vehicles only transfer about 20% of the energy into movement, the rest is turned into things like sound, light and wasted heat.

In most cars we burn a fossil fuel to generate heat (Figure 1) (zcemb63, 2009).

This can basically be described through the Ideal Gas Law:

  • P=pressure
  • V=volume
  • n=gas (moles)
  • T=temperature
  • R=constant used to account for the different units with which pressure, volume and temperature can be measured.

This heat causes expansion which moves a piston. Then the heat is released and the piston moves down, then the cycle is repeated and the fuel is ignited again. We see that a lot of energy that is meant to move the car gets wasted as the heat is vented as well as other ways. So while gasoline is very energy dense the wasteful use of it just results in more energy being wasted.

Introductory Electricity and Magnetism

Understanding some basics of electricity and magnetism is essential for us to understand how we get our electricity. Electricity, with the exception of most photovoltaics (PV) comes from the spinning of magnets to move electrons. This means that electricity generated from wind, water, burning of fuels, and even nuclear energy and some forms of solar energy (solar thermal) is produces using these basic concepts.

Magnets generate a field that move electrons. Using this pushing and pulling we are able to use magnets to move electrons. Moving electrons is what we call electricity. In generators, we spin the magnets and wires relative to each other either with steam from heated water or directly with wind or water to generate electricity. It is a commonly held misconception that the + and – for magnets correspond to a lack of or abundance of electrons, but it is actually the spin of electrons and the spin of the electrons makes them move. These nuances are probably not important for at an introductory level to understand, but that magnets can be used to move electrons is very important.

If you take apart an electrical engine you can see coils of wire and magnets. This is because electrical motors (Figure 2) are the reciprocal of electrical generators (Figure 3). Generators spin magnets to move electrons (electricity), electrical motors take the moving electrons to spin magnets that spin the axle.

Please note that in the motor the electricity goes in, and the green arrows demonstrates the movement, while the generator on the right shows a crank that can be spun that then leads to AC voltage going out. Both of these diagrams demonstrate objects that could be reversed (electricity going into either would result in movement coming out, or movement going into either would result in electricity coming out).

Obviously, there are many more nuances in this field such as why magnets attract or repel certain spins of electrons, but for purposes of this unit, simply understanding that magnets generate a field which can move electrons and the inverse is all that is necessary.

Introduction to Radiant Energy

Radiant energy is important to understand for many reasons including so we can understand how we generate electricity through photovoltaics (PV) as well as how global warming occurs.

Radiant energy can be thought of as the energy that comes from the sun. There is more to it than that, but that is the basic understanding we will need. This unit basically requires us to understand that radiant energy goes beyond the visible spectrum of light. For purposes of this unit we will use the term ‘light’ to refer to visible light and radiant energy refers to the broader electromagnetic spectrum (Figure 4) that come from the sun and includes visible light.

Some examples of energies from the sun we can’t see include ultraviolet and infrared energies as well as radio waves, x-rays, and gamma rays. While one can accept that global warming is happening without understanding these types of energies, understanding how global warming occurs requires at least a basic understanding of this spectrum. We are all familiar with the fact that light warms things, but we may not realize exactly how that occurs. Using the understanding of thermodynamics previously established we can move to some of its applications and understand how light heats things. If we understand that light is just a form of energy, we can understand that as light reflects/bounces off of a surface some of the energy doesn’t reflect. Different surfaces have different albedos, the ratio of reflected radiant energy to total radiant energy. Objects like mirrors bounce off most of the radiant energy and have a high albedo, objects that are dark in color like deep water and most roads absorb most of the radiant energy that hits them and have low albedos. This has many effects, some of which will be discussed later, but here we simply need to know that we experience most of the energy absorbed as heat. This is easily observable by seeing that different objects have different colors. Some of the light that hits them bounces off and reflects into our eyes allowing us to observe some colors. A truly black object will look the same whether or not there is light because no light reflects from of a black object. This leads us to the understanding that light and other radiant energies can be absorbed. Our daily lives have let us understand that dark objects generally get warmer in sunlight than lighter objects which allows us to reframe and shape things we already know to the important concept that light is a subset of radiant energy.

As some radiant energy gets absorbed even though most is reflected, the reflected portion is often at a lower wavelength since it has less energy.

Once we internalize that light is energy, it is then an easy step to see that light energy can be transferred into other kinds of energies. Light to heat is an easy one since we have so much experience with it, but photovoltaics is another important connection. Photovoltaics (PV) is a very complex topic, but let us get a simplified general framework before going deeper. PV allows us to transfer solar energy into electrical energy. Electrons, for the most part, orbit around the nuclei of atoms. They are bound by the electromagnetic force (positive and negative charges are attracted to each other), but with enough energy they can be moved. Photovoltaics takes advantage of this by using light to supply the energy to electrons in specific circumstances to get those electrons moving, the moving electrons being electricity.

A photovoltaic cell (Figure 5) consists of three main parts: a region overloaded with electrons and their negative charges (N-type), a region with a deficit of electrons (P-type), and a junction between those regions that is neutral that acts as a diode (PN-junction) that ensures the electrons only flow in one direction. When solar energy hits the N-type region it supplies the electrons with enough energy to be released; they flow from the N-type region through the PN-junction and into the P-type region. However, as they are drawn to the P-type region the electrons keep going through to move through wires to become electricity.

Overview of Energy Usage

Roughly one third of the energy in the USA is intended for non-electric transportation, one third for electricity, and one third is intended for other things such as heating and industrial uses. As Figure 6 shows, roughly 67% of all energy we use is wasted. Energy intended for transportation has an efficiency of about 20% and energy for electricity has an efficiency of about 35%. Other uses of energy are a little more efficient, but the overall efficiency of energy we generate is about 33% with 67% wasted.

The relative value of these numbers has not changed significantly in decades, just the overall amounts and the sources of energy. The wasted energy is in large part due to the inefficiencies of energy transfer, especially chemical to thermal, but also come from other places.

Solar and wind and natural gas have increased as sources of energy with the use of coal decreasing. 80% of our energy still comes from burning of fossil fuels, this is not significantly different from decades ago. The increase in wind and solar does not yet keep up with our increased demand for energy, with natural gas filling in most of that gap. Looking at these numbers, an important takeaway is that while individual actions can have an impact on energy, societal/governmental actions are now required to address the amount of fossil fuels being consumed. Fossil fuels lead to global warming which is and will continue to have horrific impacts which will be addressed in the next section. It seems that our world does not have a desire to reduce demand of energy, in fact our energy consumption has increased quite a bit, leaving the only real solution being a change in our sources of energy.

Global Warming

If the world doesn’t do anything… the very social stability of human systems could be at stake.

This is how Rajendre K Pachauri started off the press conference announcing the 2014 IPCC report, the still universally recognized and acknowledged comprehensive report on climate change. This means that governments and societies will be pushed and broken because of climate change, e.g. the Syrian Civil War which started in large part due to events from climate change (Fischetti, 2015). Given this report and other global events, along with their own research the US Department of Defense declared Global Warming to be a threat multiplier (United States Department of Defense, 2014), making it clear that even the most Leviathan of Byzantine bureaucracies are sure of global warmings reality and huge impacts.

Global warming is the increase of energy in the Earth’s system. For millennia, there has been an equilibrium in the amount of energy, but in the last 100 years that equilibrium has been thrown off by a precipitous change to our atmosphere. This change is primarily from greenhouse gases being introduced into the atmosphere by humans burning fossil fuels. These fossil fuels are sources of chemical energies that we use as described above. The earth has been storing that carbon and energy in the form of fossil fuels for hundreds of millions of years, and over the course of just decades we have released much of those stores into the atmosphere; millennias worth of carbon is being put into the atmosphere every single year by our misuse of energy. This is so rapid that life on Earth is having a difficult time adapting. The Earth itself will be fine, but the amount and diversity of life on Earth is being reduced at alarming rates.

Global warming occurs as radiant energy gets through the atmosphere, then partially reflects off of the surfaces of the Earth (Figure 7). Some stays and what reflects, now at a lower wavelength, in part does not escape through the Earth’s atmosphere. As you can see in Figure 7, a huge amount of energy is reflected back to the Earth that initially reflects off like someone blocking a basketball shot. One of the main things that traps the energy is atmospheric carbon dioxide. When there is less CO2 in the air more of the reflected energy escapes into space, but more CO2 in the atmosphere means more energy gets trapped. In 1920 the amount of CO2 in the atmosphere was about 291 ppm, and in 2020 the amount was over 410 ppm, an increase of 40% in 100 years. This is catastrophic and as you can see in Figure 8 it is getting worse and worse with no clear signs of improving.

Global Warming is Real

Humans are causing global warming. Unfortunately many people try to confuse things and make it seem like there is scientific debate on human caused global warming. There is not. 97% of scientific articles support the fact that climate change is happening, with the remaining 2% that don’t support it having critical errors or are non-reproducible (Benestad et al, 2015. It is unfortunate that many people seem to have an agenda that leads them to try to confuse people into not believing humans are causing an increase in global warming, but it must be understood that global warming is real and is currently being increased by humans.

In addition to there being scientific consensus, the US Department of Defense (United States Department of Defense, 2014), and in 2014 even Exxon Mobil acknowledged that it knew about global warming and has been actively spreading disinformation about global warming since 1977 (Hall, 2015). In 1977 James Black, the senior scientist for Exxon Mobil stated:

In the first place, there is general scientific agreement that the most likely manner in which mankind is influencing the global climate is through carbon dioxide release from the burning of fossil fuels

And then continuing

present thinking holds that man has a time window of five to ten years before the need for hard decisions regarding changes in energy strategies might become critical

We must acknowledge that given the known science about radiant energy, thermodynamics, and greenhouse gases that global warming is real. It is being driven by humans. We must adapt our energy strategies, our sources of energy. Anyone who argues against that reality is either ignorant of reality or has an agenda and is trying to spread disinformation for their own purposes.

Atmospheric impacts

Global warming is having a large impact on our atmosphere. The most obvious is the increase in temperatures, but there are other impacts associated such as increasing extreme weather events and changing weather patterns.

Increased CO2 (and other greenhouse gases) in the air causes more energy to be absorbed by the Earth’s system. This leads to the atmosphere warming which then leads to many other impacts. In addition to it just generally being uncomfortable over more of the inhabited planet the increase of energy increases the rates of extreme weather events (Figure 9).

Instead of many small rains in an area there will be fewer, but larger rains. Also stronger hurricanes and more tornadoes as there is more energy to be released. Even areas such as Eastern Europe, which are expected to be less impacted by these changes, are now seeing tornadoes as have not been seen in memory. The last few years have had more and more weather events that cause flooding and other damage.

The NOAA even had to change their definition of normal when it comes to weather (NOAA, 2021). Temperature and rain events are increasing so much that our definition of normal now includes more heat and rain events that cause flooding than before.

Desertification and other land impacts

There are many effects of global warming on our land, but a few of the worst will be discussed here such as desertification, other water scarcity, and a reduction in the nutritional quality of food.

The heat has other impacts beyond just being hot. Increased heat means that more water gets evaporated. This leads to some areas getting dried out more, and also getting less rain, while other areas get even more rain. While there will be more rain overall, most of it will fall over oceans and large swaths of land will be turned into deserts. This creates a vicious cycle where drier areas get even drier as the warmer air feels drier with the same amount of trapped moisture (Figure 10). The image on the left is if we stop producing greenhouse gases now, and on the right is if we don’t cut them until 2050. This further reduces the amount of land on which food can be produced.

An issue similar to the desertification of land is water scarcity. As discussed, there will be more rain in some areas, but less rain in other areas. This results in large population centers being without enough water. This water scarcity is thought to be one of the main drivers of the oncoming political instability that could lead to increased wars and terrorism (US DoD, 2014).

Global warming is also related to a reduction in the nutrient density of foods. Some people have ignorantly said that increased carbon dioxide will help farming, but instead of helping, high carbon levels actually reduces the nutritional value of plants (Myers et al, 2014). So, global warming not only reduces the amount of land upon which we can grow crops, but the driver of global warming (increased CO2) also reduces the nutrients found in the food we can produce.

Ocean impacts

Global warming and its drivers are causing many issues with the oceans. One of the more well-known ones is polar ice melting changing habitats, but the ocean levels are rising, and acidification are to be contended with as well.

As the atmosphere increases in temperature so do the oceans. This rise in temperature is melting sea ice. This causes biomes to change as many animals depend upon floating sea ice for various reasons. However, this is not the worst part of the melting sea ice, that is the change in albedo. Sea ice is relatively reflective, reflecting up to 90% of the light that hits it, but deep oceans are relatively dark bodies, absorbing up to 90% of the light that hits them. This is a huge increase in the amount of energy absorbed in these regions. This is a vicious cycle that means the waters get warmer and warmer as more and more ice melts with the caveat that melting ice does very temporarily decrease the temperature.

It is not only sea ice that is melting, land ice (glaciers) is also melting at alarming and ever increasing rates. Atmospheric temperatures rising is a primary cause of the ice melting, but the industrialization of our planet leads to soot landing on the ice which darkens it causing it to absorb more energy and melting faster. This melting of the ice is leading to oceans rising as all of that water eventually finds its way into the oceans. As the oceans increase in temperature, there is also thermal expansion of the water to contend with. This rise in the oceans is going to be catastrophic. It is estimated that more than 340 million people currently live in areas that will be continually flooded by 2050, and 630 million people currently live in areas that will be continually flooded by 2100 (Kulp and Strauss, 2019). Many models suggest that over 1 billion people live in areas at risk, with a 1m rise in flood plains being possible. These people will have to go somewhere, and when there are hundreds of millions of people, possibly a billion, who have to move it is difficult for them to be absorbed by existing areas leading to more instability.

Teaching Strategies

The overall approach of this unit will be an inquiry driven, constructivist approach. Both of those things by their nature are student-centered. Students are supposed to generate something (a game or lab or…) to teach someone something about global warming as well as creating a plan to help our planet reduce global warming. They are presented with this at the beginning and tailor their experiences towards these goals. This is generally the preferred methodology to help students gain a deep understanding of ideas as opposed to rapidly acquiring then forgetting discrete facts (Maheshwari and Thomas, 2017). This will be accomplished by blending problem-based-learning (where possible) and a project based learning approach. Having students learn in this method is messier than traditional models, but their learning is deeper and more transferable to their everyday lives (Jones, 2006). This will also allow students to construct their own meanings and internalize ideas more deeply. To avoid the misconceptions sometimes associated with these methodologies I will also be using many of the techniques discussed by Schwartz et al in their contrasting cases research out of the AAA Lab in Stanford (Schwartz et al, 2011) and simulations (Chin, 2010), especially at the onset of parts of the students learning. So students will not have a ‘pure’ PBL experience, but instead will have many self-guided experiences with specific benchmarks that I have set. Their solutions are still open-ended, but I will be guiding them more than I would like. This is, however, necessary as the students I teach are coming from many different schools and this is a norming experience for them.

Throughout all of these experiences I would strongly encourage you to have your students use science notebooks, especially for labs. I prefer the Carnegie Notetaking format. Then weekly I collect them and as much as possible try to create a written dialogue with the students based on their observations, conclusions, and the questions and summaries they write.

This unit is presented as if most activities and experiments are teacher led, however I have found that presenting the students a menu of activities and letting them choose which ones (with a few required) they use to construct enough of their own ideas for the larger projects in the sections/overall to be very effective. Doing everything in this unit would take at least a quarter, and more likely a semester, and could be expanded with more detail to take an entire course. It is suggested different students do different pieces of the unit.

Essentially, in this unit the students will be presented with the dual projects of teaching someone something about energy and global warming while also designing a plan to reduce global warming. Teaching someone something about global warming could be classified as project based learning and the plan to reduce global warming could be classified as problem based learning. Then through a few common experiences such as building motors, doing energy audits, or using calorimeters students will start to develop understandings underlying energy and how we use it. After that students will be able to choose certain activities/labs to help them understand the key ideas for their solutions to the problems.

The population of students with which I work have a low reading level and usually very little background knowledge in formal science, so it is important that the students gain experience with concepts and construct their own meanings including making their own observations to create their own meanings. Then I can help them find the language that formal science has placed on these ideas that they have formed. This avoids science from becoming ‘death by definitions’ and makes it full of relatable experiences with language to help communicate those experiences to other people.

Energy, Energy Transfer, and Work

To teach about energy, energy transfer, and work I spiral through those concepts. Touching on some of the concepts at an introductory level then continuing at a deeper and deeper level until the students have some deeper understandings of the concepts. I like to start with asking the students what energy is and examples of it. Then after they give their definition and examples we will do some of the ramp exercises discussed in the content section.

We will look at ramps and half pipes and convert GPE and KE back and forth. I often start this part with the clip from The Simpsons where Homer tries to jump Springfield Gorge https://www.youtube.com/watch?v=FgrDAelryUo and use that as a simple model.

Then students can set up their own tracks with matchbox cars and tracks or other equipment depending upon what you have. Fancy equipment like Vernier probes and tracks are useful, but matchbox cars or even marbles on pieces of cardboard with the edges bent up to form a V to create a track are enough to get a good idea of the concepts. If you are using the lower tech versions, discussions of error and precision (or lack thereof) are necessary, but the general ideas of GPE to KE can be seen and constructed by the students.

After this we will go back to the Simpsons video and practice with the equations, this is also good practice of estimation and basic numeracy. We will then go back and have the students do the calculations from their experimental values.

This process does take more than a day. Depending on how the timing falls on certain days, when there is a good stopping point with about 30 minutes left, I will start a part of a lesson related to formalizing knowledge of energy and its transfer. Energy Transfer Intro Lesson (below) lays out how this can be done. It will be presented as one single lesson here to help with modular implementation, but I prefer to do it as 2-half lessons spread out over 2 days.

After the students have completed these lessons refer them back to their ideas of energies from day 1. We discuss and look for energies that can be added. On this day I will often ignite isopropyl alcohol fumes in a 5 gallon water jug at the start of class, then do it again after the discussion if students have yet to discuss the ideas of light, heat, sound, or chemical energy. A bouncing tennis, basket, or superball can be used to demonstrate the idea of elastic energy as well. If/When you bounce these items it is suggested to only let them bounce once or twice or the students will notice the energy loss. This is not a huge problem, but at this point that is a conversation that is likely to confuse more people than it helps. It can be a useful point in conversation later, but at the very beginning the demonstrations (distinct from activities the students do) should be as clean as possible from ‘noise.’ Making a ‘Rollback Can’ is another way to have the students experience elastic energy and can also be used to introduce the concept of frame of reference

After these discussions I will often next proceed into LoL charts. I don’t remember where I initially got this idea, but this blog discusses them reasonably well.

https://kellyoshea.blog/2012/03/05/energy-bar-charts-lol-diagrams/

After we practice LoL charts with some of the things examples from class, the students are then given the task of designing their own activity/experiment, write up a procedure, and then create and estimate/calculate LoL charts. The next day students run their experiments and revise their write-up and the day after that they do some of each other’s experiments.

Sometimes, if time permits, on the second day of the LoL experiments I will do the peanut butter and jelly activity where they write directions to make a PB&J sandwich and I then mess up the sandwich due to lack of clarity etc… in their directions. This can be a lot of fun, but you should be wary of doing this activity if you have a lot of food insecure students. A version of this with tying a knot can also be a lot of fun. This activity helps the students understand how to write protocols, but also helps them learn some empathy if there is ever something unclear in the protocols you give them.

At this point I give a mini-project for the students where they either must design a Rube Goldberg Device to accomplish some task or in a group design non-percussive instruments with which they can together play a recognizable song. This helps students, with proper guidance on their reflections, to use an innate understanding of energy transfer to do something useful, which helps them understand work.

Introductory Thermodynamics

For this part we do a fair amount of experiments. Some controlled explosions such as isopropyl alcohol fumes combusted in a bottle are a great starting point. There are also other experiments related to types of chemical reactions, the ideal gas law, and simulations related to thermodynamics and global warming that are quite useful here. For the simulations I let the students explore as they will while other students perform the experiments. Based on availability of lab materials you may be able to have all of the students do experiments about combustion, single and double replacement, and decomposition reactions, but having half do simulations while others are doing labs is a reasonable way to split the class if materials are scarce.

Other demonstrations that can be used to highlight some concepts include the ‘can crusher’ activity where you heat up a soda can with a little bit water in it until the water turns into steam, then you quickly flip the can upside down in an ice water bath and the can contracts as the steam condenses. This is a good experiment that highlights the ideas of pressure, partial vacuums and also the ideal gas law. There is also a lab outlined below where carbon dioxide is produced from mixing baking soda and acetic acid in a way that allows students to safely observe the ideal gas law from their own experimentation. Between these activities students can often intuit Charles’ law and Boyle’s Law.

At this point, if students are highly motivated you may want to let a group create a sterling engine. Here is a decent way to make one, https://www.instructables.com/Simple-coke-can-engine/

but pay attention to the note about steel cans. Also the properly bent paper clips can be substituted for the spade connectors.

Introductory Electricity and Magnetism

To start out this section of the unit I recommend telling the students they will build an electric generator. Ask them what they know about these things, if they are stuck many students will have heard of Tesla cars and/or Tesla coils. Then through this discussion you can help them figure out many bits of knowledge they don’t know in terms of how to build motors/generators. Tell them they will have some experiments, then they will have to synthesize their knowledge to build the generators.

There are many options for this, but one wayis to have the students experiment with magnets and coils of magnetic wire. An experiment to help the students understand magnetic fields is to take some 30cm x 30cm of cardboard, raise the edges with strips of the cardboard, until there is a raised edge slightly taller than magnets you have. Then stretch 2 layers of saran wrap or similar clear material across the top and secure it. You can safely place a refrigerator magnet under the saran wrap and with an additional magnet in each hand students can ‘shoot’ the magnet by placing the magnets in their hands near the first magnet. For advanced students this is also a way to introduce vectors. This gives ideas of fields and also how different poles of magnets react to each other.

You can also create an envelope with overhead projector sheets (or similar thickness clear plastic) cut in half and tape 3 of the edges securely. Then place iron filings into this pocket and seal the top. Then place a magnet near it. This allows students to use their own observations to construct good ideas on what the fields of magnets look like.

Similarly a ferro-fluid can be made by mixing oil and iron filings. Strong magnets (n-42 or higher) placed near the bottom of the container with the ferro-fluids can help students visualize magnetic fields. If you feel like creating an electromagnet out of a step bore bit on a drill you can create some very cool visuals like this one: https://www.youtube.com/watch?v=pIZrHCXIPkY

You can also magnetize tools such as screwdrivers or drill bits. Wrap magnetic wire around a screwdriver and pass electricity through the wire. An electrophoresis power supply generally works for this at a safe amperage. The the screwdriver will be magnetized relatively quickly. This will help the students see that there is a relationship between electricity and magnetism. This can also be achieved by wrapping 100 or so coils of insulated magnetic wire around a thin ferrous cylinder and dropping a something ferrous through the cylinder while the magnetic wire is electrified. These items don’t stay magnetic for too long, but it helps students see the connections between electricity and magnets. Between this activity and the others that allow students to visualize the fields of magnets the ideas of how electricity and magnets work together should start to form in the students with some guidance. Things like orthogonality and the right hand rule may require direct instruction, but those specifics usually only need to be used to refine the specifics of the ideas the students construct.

After this I would recommend having the students build a simple electric motor. The steps for this are outlined in classroom activities below.

Once they have the idea of the relationship between electricity and magnetism from the earlier activities, combined with the simple electric motor, students should be able to build an electric generator from magnetic wire, magnets, a water bottle to act as a base, a pencil for the axle, and some paper clips to hold the pencil in place. To help them transfer concepts from the motor to the generator you can wire some LED’s out of the wires coming out of an old speaker, then lightly use the speaker as a drum, which should send an electric signal back out of the wires. Discussing the reversibility of motors/generators, to help the students understand that just as electricity can create electromagnets, magnets can generate electricity. Students can also investigate using a fan, and spinning the blades and see that electricity comes out of a fan when the blades are spun to assist them in building the generator

Introduction to Radiant Energy

Radiant energy can be difficult for students to understand beyond visible light. The relationship between radiant energy and thermal energy is one with which they are familiar if they are reminded of this. Discussing walking barefoot on black asphalt helps orient the students to their prior knowledge.

If students are still struggling with this, you can sand one soda can to make it shiny, and paint black another. Then put some water and a thermometer in them and place them in the sun. If you are worried about the insulating properties of paint, paint one of the cans with reflective paint instead of sanding. Building a solar oven or filling a thin black trash bags with air, sealing it tightly, then placing it in the sun are also activities that would allow students to use their observations to draw conclusions about a lot of the underlying ideas of radiant energy.

Discussions of how we see things and even reproducing Newton’s prism experiment can be useful here as well. This can help students realize that maybe there are elements of ‘light’ that we do not initially see. Discussing the ‘Predator’ movies or similar that highlight infrared energy, something that humans can’t see, but other things can can help the students think beyond the visible spectrum. Sometimes discussion of bees and other animals that see beyond our visible spectrum can be fruitful here.

Now we get to the part that people often don’t ‘get,’ how is it that carbon dioxide, something that is transparent to visible light, is opaque to some energies? To help facilitate students to understand this you can have the students generate carbon dioxide with baking soda and vinegar in a vacuum Erlenmeyer flask. Using a thermometer through a 1-holed stopper (placed after the reaction is completed) and placing a balloon over the vacuum outlet to release pressure without losing gas you should see a temperature increase. In another flask do the same set-up, but with the vinegar and baking soda in weigh boats so they don’t mix. Take measurements at many times of the day. If you are with an advanced class, you can have them figure out the design of this experiment. Then discuss this experiment ad nauseum. Beat home the fact that the carbon dioxide in the first flask was really the only difference and the reason why it got so much warmer.

Letting the students experiment with solar cells, using them to move motors or light a lightbulb is also very useful here. It shows how solar energy can be used to generate electricity.

Overview of Energy Usage

This part seems rather didactic. One can discuss electricity audits and use Kill-o-Watt meters to measure the amount of energy of various items in school and possibly at home if you have enough to send home with students. Then, based on this information discuss how much energy we use. Having charts with information about energy used by vehicles, common items like computers and refrigerators etc… will allow students to do an energy audit of their current lives. Depending on where you live, discussions of insulating houses and new windows etc… may also make sense.

Then give the students data on USA and/or worldwide energy usage (Figure 6). At this point remind them again of the energy transfer intro lesson and point out the fact that almost all energy we use comes from chemical energy which comes from the sun, and that producers are the only things that output chemical energy. When combined with the information from the carbon dioxide experiments we can see that the way we use energy is causing global warming. Based on this and Figure 6 they can see how we are causing global warming. Failing reducing what we want, things like transportation and air conditioning, the only choice is changing our sources of energy.

Global Warming and its impacts on the Atmosphere, Oceans, and land

To start this part you could use a clip from futurama https://www.youtube.com/watch?v=B2LB4Up6hWc

that in a funny way shows a little bit about how global warming occurs. There is a joke from 1:29 to 1:35 I recommend fast forwarding though. This gives a quick idea that carbon dioxide leads to thermal energy being trapped.

Watching ‘An Inconvenient Truth’ or doing a webquest or reading current event articles are good ways to see some of the effects.

There are a few simulations that also help this part. Most students with which I am familiar have heard of global warming and are somewhat familiar with its consequences. Wherever you live the local impacts may vary, but a quick search of your local paper will find some recent stories.

If there is any doubt about Global Warming it is easy to cite the Earth’s moon. The average temperature on the moon’s surface is about -38C, and the average temperature of the Earth’s surface is about 14C. That is a 52 degree difference despite receiving almost exactly the same energy per square meter. The Earth must traps more of the sun’s energy, that is global warming. Once that is established, and earlier experiments demonstrate that carbon dioxide traps heat, there can be no doubt that adding carbon dioxide increases the energy trapped on the Earth from the sun.

Based on all of this, students can develop their own plans for the reducing global warming, be it individual things they do or things that governments can implement and how they can be accomplished. Students should also take the ideas they learned and develop an experience that could teach someone some aspect of their learning.

Classroom Activities

Energy Transfer Intro Lesson

  • Ask students how they feel when they haven’t eaten for a while, then how they feel an hour after eating. Then ask them why they feel a difference. This is because they take the chemical energy from the food and use that energy.
  • Hand out the chart (Figure 11) and discuss the person in the upper left.
  • Students in their notebooks write about the plant energies.
  • Students fill in the energies in and out from a car.
  • Students develop their own examples independently
  • Students share their examples with others in their groups.
  • After that there is a multi-step energy transfer that they should think about and develop.

After students have worked on these, they should develop LoL charts for each of the examples.

To wrap up their learning students can write a paragraph in their journals about what kinds of energies are mostly going into their examples, if many of them have electricity going in, make sure that there is an example on the board showing that electricity primarily comes from chemical energy, which primarily comes from fossil fuels.

Ideal Gas Law Lab

Materials:

  • 30ml Syringe with threaded end
  • Cuvette cap
  • Luerlok syringe end cap
  • Silicon oil
  • Sodium Bicarbonate
  • 5 M Acetic Acid

Lab Instructions

  • Wear your safety glasses!
  • Lubricate the black rubber seal of the plunger with silicone oil.
  • Measure out NaHCO3.
  • Place the NaHCO3(s) directly into the cuvette cap.
  • Fill the syringe barrel completely with water. Place your finger over the hole to form a seal.
  • Float the vial cap containing the solid reagent on the water surface.
  • Release the seal made by finger to lower the cap into the syringe barrel without spilling its contents.
  • Install the plunger while maintaining the syringe in a vertical position. Push plunger as far down as it can go.
  • Pour the CH3COOH into a small beaker. Draw calculated volume of the solution into the syringe.
  • Twist on the syringe cap.
  • Shake the device up and down in order to mix the reagents. Gently help the plunger move up the barrel.
  • Record the volume of gas generated.

Simple Motor

Materials:

  • 2 – 6”x1” aluminum foil
  • 2 – metallic paper clips
  • 2 – N-30 magnets
  • 2m of 20 gauge magnetic wire
  • 1 – plastic or styrofoam cup
  • 1 – 9V or D battery
  • masking tape

Lab Instructions

  • Wind wire into a coil that is 1-inch in diameter
  • Attach the magnets to either side of the bottom of the cup and set it aside
  • Unfold one arm of the paper clips
  • Attach one end of a foil strip to the longer end of a paper clip; repeat for other paper clips
  • Place and secure the paperclips to either side of the bottom of the cup so that the unfolded ends become two cradles/hooks
  • Place the coil by its ends onto the cradle parts of the paperclips
  • Touch the ends of the foil strips onto the 2 electrodes of the battery

Resources

Bibliography for teachers

Benestad, R. E., Nuccitelli, D., Lewandowsky, S., Hayhoe, K., Hygen, H. O., Dorland, R. van, & Cook, J. (2015, August 20). Learning from mistakes in climate research. Theoretical and Applied Climatology. https://link.springer.com/article/10.1007/s00704-015-1597-5.

This article discusses the scientific consensus on climate change and some of the deficiencies in the research that counters human driven climate change

Chin. (2010). Practicing Versus Inventing with Contrasting Cases: The Effects of Telling First on Learning and Transfer https://aaalab.stanford.edu/assets/papers/2011/Practicing_versus_inventing.pdf.

This reading is very useful in terms of framing why constructivism is so important. Students grow and learn so much more when they construct their own meaning and then have educators help refine that meaning rather than listen to information first then try to apply said information. It is important to check and correct for misconceptions, but still students do much better after exploring on their own.

Chase et al (2011). Explaining across contrasting cases for deep understanding in science: An example using interactive simulations https://aaalab.stanford.edu/papers/Explaining-across-contrasting-cases-for-deep-understanding-in-science-an-example-using-interactive-simulations.pdf

This article helps explains ideas on how to integrate interactive simulations in a constructivist classroom

Dean, T. (2008). The human-powered home choosing muscles over motors. New Society.

This book offers many ideas for projects you could have your students do to try to get an understanding of electricity and energy transfer

Fischetti, M. (2015, March 2). Climate Change Hastened Syria’s Civil War. Scientific American. https://www.scientificamerican.com/article/climate-change-hastened-the-syrian-war/.

This article discusses some of the lesser thought of consequences of global warming and its larger impacts. Understanding some of these things help us understand some second and third level consequences of global warming.

IPCC, 2014: Climate Change 2014: Synthesis Report.

This report is a summary of many of the findings of the United Nations International Panel on Climate change. It is a good source of information on climate change as well as graphs and diagrams that can be used to help students learn.

Kulp, S. A., & Strauss, B. H. (2019, October 29). New elevation data triple estimates of global vulnerability to sea-level rise and coastal flooding. Nature News. https://www.nature.com/articles/s41467-019-12808-z.

This article discusses how flooding may affect populations.

Maheshwari, G., & Thomas, S. (2017, May 22). An Analysis of the Effectiveness of the Constructivist Approach in Teaching Business Statistics. Informing Science: The International Journal of an Emerging Transdiscipline. https://www.informingscience.org/Publications/3748.

Background information on constructivist teaching methodologies

Myers, S. S., Zanobetti, A., Kloog, I., Huybers, P., Leakey, A. D. B., Bloom, A. J., Carlisle, E., Dietterich, L. H., Fitzgerald, G., Hasegawa, T., Holbrook, N. M., Nelson, R. L., Ottman, M. J., Raboy, V., Sakai, H., Sartor, K. A., Schwartz, J., Seneweera, S., Tausz, M., & Usui, Y. (2014, May 7). Increasing CO 2 threatens human nutrition. Nature News. https://www.nature.com/articles/nature13179#citeas.

This article discusses that plants in high carbon (greater than 300 ppm) atmospheres have less nutrients.

United States Department of Defense. (2014). Quadrennial Defense Review 2014.

This is one of the first times that the US DoD publicly acknowledged climate change as a threat to US security

Reading list for students

Hall, S. (2015, October 26). Exxon Knew about Climate Change almost 40 years ago. Scientific American. https://www.scientificamerican.com/article/exxon-knew-about-climate-change-almost-40-years-ago/.

This article discusses the, at the time, recent revelations by Exxon that they have been studying global warming since the 70’s and were spreading disinformation about it to allow them to continue with fossil fuels

Kamkwamba, W., Mealer, B., & Zunon, E. (2016). The boy who harnessed the wind. Puffin Books.

This book is a good read for students as it helps them see that individuals can have agency in how we generate and use energy as well as just generally take control of their lives by taking action when they see a need

The new U.S. Climate Normals are here. What do they tell us about climate change?| National Oceanic and Atmospheric Administration. (2021). https://www.noaa.gov/news/new-us-climate-normals-are-here-what-do-they-tell-us-about-climate-change.

This article discusses how weather events and temperatures have changed so much over the past few decades that we need to re-define what ‘normal’ means.

Materials for classroom use

https://phet.colorado.edu/sims/html/energy-forms-and-changes/latest/energy-forms-and-changes_en.html

Energy Transfer

https://phet.colorado.edu/en/simulation/energy-skate-park

Mechanical Energy Conservation

https://phet.colorado.edu/en/simulation/gas-properties

Gas properties

https://phet.colorado.edu/en/contributions/view/3505

Thermodynamics of skating

https://docs.google.com/document/d/1m08RUfZ4E8zuFC6aEEv9KcH_lxl_c89GbJodjyp8i4k/edit

EM Spectrum phet guide

https://phet.colorado.edu/en/contributions/view/2820

Conservation of energy phet guide

https://phet.colorado.edu/en/simulation/gravity-force-lab

Gravitational Force

https://www.thephysicsaviary.com/Physics/Programs/Labs/ForceFriction/index.html

Friction simulation

https://phet.colorado.edu/en/simulation/greenhouse

Greenhouse effect simulation

https://phet.colorado.edu/en/simulation/glaciers

Glacier simulation

Figures

Figure 1 zcembl. (2009). Gas Power Cycles – Mech Engineering: Thermodynamics – UCL Wiki. UCL Wiki. https://wiki.ucl.ac.uk/display/MechEngThermodyn/Gas+Power+Cycles

This is a picture of how most gasoline engines work

Figure 2 Brushed DC electric motor. (2021, April 11). In Wikipedia. https://en.wikipedia.org/wiki/Brushed_DC_electric_motor

How electric motors work

Figure 3 AC (Alternating Current) Generators. (n.d.). Museo Das Communicaos Wiki. Retrieved May 15, 2021, from http://www.cmm.gov.mo/eng/exhibition/secondfloor/MoreInfo/2_4_1_ACGenerator.html

AC Generator

Figure 4 Electromagnetic radiation. (2021, May 29). In Wikipedia. https://en.wikipedia.org/wiki/Electromagnetic_radiation

Visualization of the electromagnetic spectrum

Figure 5 Photovoltaics and electricity – U.S. Energy Information Administration (EIA). (n.d.). Photovoltaics and Electricity. Retrieved May 16, 2021, from https://www.eia.gov/energyexplained/solar/photovoltaics-and-electricity.php

Image of a solar cell

Figure 6 Estimated U.S. Energy Consumption 2019. (n.d.). Lawrence Livermore National Laboratories. Retrieved March 25, 2021, from https://flowcharts.llnl.gov/content/assets/images/energy/us/Energy_US_2019.png

Estimated energy consumed, USA 2019

Figure 7 Der natürliche Treibhauseffekt. (n.d.). KlimaNavigator. Retrieved May 21, 2021, from https://www.klimanavigator.eu/dossier/artikel/011967/index.php

Representation of radiant energy and its interaction with the Earth and its atmosphere

Figure 8 Climate Change: Atmospheric Carbon Dioxide. (n.d.). Climate.Gov. Retrieved May 21, 2021, from https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide

Carbon Dioxide levels over the last hundred years

Figure 9 Met Office. (n.d.). What is climate change? Retrieved June 15, 2021, from https://www.metoffice.gov.uk/weather/climate-change/what-is-climate-change

Graph of the increase in severe weather events

Figure 10 Future of Climate Change | Climate Change Science | US EPA. (n.d.). Future of Climate Change. Retrieved May 15, 2021, from https://19january2017snapshot.epa.gov/climate-change-science/future-climate-change_.html

Projection of precipitation changes

Appendix

NGSS Standards

  • MS-PS1-1
  • MS-PS1-2
  • MS-PS1-4
  • MS-PS1-6
  • MS-PS2-5
  • MS-ESS3-5
  • MS-ESS3-2
  • MS-ESS3-3
  • MS-ESS3-4
  • HS-PS2-6
  • HS-PS1-6
  • HS-PS2-5
  • HS-PS3-2
  • HS-PS3-3
  • HS-PS3-5
  • HS-LS1-7
  • HS-ESS2-4
  • HS-ESS3-5
  • HS-ESS3-1
  • HS-ETS1-3