Strategies
This will be an inquiry based unit. I will begin this unit on global warming by asking the students to list what they consider to be the top five concerns facing us as human beings on this planet. I will ask them why they have listed these issues as their top five. I expect that the top five will be related to their own personal concerns of safety and well being. It is my hope to be able to open up a discussion of the students' personal concerns in order to begin to stimulate a global concern. Pittsburgh is not likely to be significantly directly affected by raising sea levels, increased storms or changing rainfall, although this is possible. Instead my emphasis is going to be on attempting to instill in students a sense of global perspective. All people must share the Earth and the poor are always the most vulnerable to fluctuations. So how do we as a people take responsibility for the global community? I will establish the relevance by stressing the need for community.
First I will ask them how much energy they use during the year. What do they need energy for? Food, transportation, heat, to have things made, the trash generated… I will guide students to realize how many resources they use and indicate that we use more energy in the US than anyone else. More than Africa and Asia combined. Where does all of this energy come from? Mostly the energy is from fossil fuels. We burn gas and oil to create most of our stuff. This leads to global warming.
What is the maximum temperature that we can live at? What is the minimum temperature that we can live at? The Earth on average is 12°C. So how can a few degrees make a difference? Rising sea level, increased frequency and severity of storms, redistributed rainfall, changing ecosystems, economic consequences…
Mostly, though, our concern must be that we don't have anywhere else to live. The Earth is our only home and there is the possibility that if we abuse it, it might no longer be livable for us. There is the real possibility that we could cause another Ice Age. If we mess up our climate there is no where else for us to go. We must all live on this planet so we must take care of it.
I will utilize constructivist methods to stimulate interest in global warming. I will do this by giving the students some experiential knowledge of global warming. First we will do an experiment on the Greenhouse effect. By shining a light on a sealed glass jar we will compare the temperature of the air inside the glass jar to the temperature of the air outside. This will indicate that greenhouse effect exists. I will have the students compare what happens if we paint the bottom of the jar white and what happens if we paint it black to compare the effects of reflectivity and albedo. I will indicate that our atmosphere acts the same. It is just like a greenhouse.
Next I will have several of the students put on body suits during class. Without increasing their normal activity we will discover that putting on an extra layer, especially if it is well sealed, will result in internal heating.
I will demonstrate the concept of the thermal expansion of the oceans by heating up a water thermometer. Why happens to the water? Why does it expand? What does this have to do with the oceans? What will happen to the oceans as they heat up? Where will the water go?
Then we will calculate the expected temperature of the Earth and Venus. I will attempt to get them to derive parts of the formula by prompting them about the required components of the formula: namely the energy output of the sun, the distance the Earth is from the sun, the reflectivity of the Earth, and the surface area of the Earth. Using this we will calculate the temperature. I will also have my students utilize this to algebraically derive the simplified version of the formula. Having done this we will determine the expected temperature on Venus and compare. Venus would appear to be habitable whereas the Earth does not. However, we know that the opposite is true. Why is this? I will let the students speculate. If they don't suggest it I will remind them of their lab and get them to realize that it has to do with our atmosphere and the greenhouse effect. Without our atmosphere we would not be here!
So what has gone wrong? Why are we concerned about the greenhouse effect? I will ask my students these questions. Let's consider the Earth. Now let's build a model. I will have the students build a model of the sun and the Earth. What happens between the sun and the Earth? How is the energy transmitted? What happens to the energy when it reaches the Earth? How do we see? What does this tell us about our globe? Let's look at some pictures of the Earth? What is the shape of the Earth? What do we see when we look at the Earth from outer space? What does our atmosphere do? Have you heard of the hole in the ozone? What was that? Why do we get a sun burn? When do we get burned the most? At what time of day? What does this tell us about light? How do we include what we know about the atmosphere in our model of the Earth? What did we learn from the "body suit" activity? Is our atmosphere like a blanket? How can we include this in our model?
Let's build a model of our chaotic climate. The students will build a rollercoaster with multiple high and low spots. We will build these roller coasters out of tracks. I will give each group a ball and have them place it in a low spot. Let's label the lowest spot -25°C then label the middle point 12°C and the highest point 40°C. What happens if you give it a very small push? What happens if you give it a slightly bigger push? What does it represent when the ball ends up at a different "temperature"? This is an indication of our climate change. If our global warming provides enough of a push maybe we it will change our climate? What would the consequence of a drastic change in our climate be? Would we be able to survive?
The students will have enough basic knowledge at this point that I will print up the background knowledge and provide it to them. After they have familiarized themselves with the scientific information I will have them split into two teams and have a debate about global warming. Half of the students will defend the statement that global warming is a serious issue and we must do something to prevent a global disaster. The other half of the class will make the argument that global warming is a myth and there is nothing that we need to do. The debate will last twenty minutes. Then we will discuss how the issues were most effectively addressed.
The culminating event is going to be for students to write the mayor of Pittsburgh and explain why we should be concerned about global warming. The paper will be a persuasive essay to convince the mayor to join other cities in the support of the Kyoto Treaty. I will provide them with information about Pennsylvania and other states that have already joined. This exercise is meant to empower the students and encourage them, since they are nearly of voting age, that local government is a powerful means of societal change.
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