The "Big Idea" for this activity is climate change, but it also involves other learning goals such as the abilities to create conceptual models of biogeochemical processes and to identify the sources (i.e. where stuff comes from) and the sinks (i.e. where stuff goes to) in these models. This exercise gives the students the opportunity to engage in systems thinking by examining and discussing the inter-relatedness of various concepts such as fossil fuels, carbon dioxide, and deforestation. Finally, the students are required to make oral presentations about their mind maps, giving them an opportunity to work on another valuable learning goal - effective public speaking.

This activity was developed for a 100-level college Environmental Science class. The activity itself takes about one hour, but requires supporting instruction to provide context for the students. Most of the students have only had high school science, and for some of them, it may have been over a decade since their last science class. I therefore assume the students are starting from scratch when it comes to the science of climate change, but I do think all of them have heard about climate change and have at least begun to form an opinion about it.

I combine the topics of Climate Change and Ocean Acidification under the heading "Life in a High CO² World" and spend roughly three hours of lecture and two hours of lab on it. I introduce this topic around week seven, after the students have learned the concepts of photosynthesis and respiration, and are familiar with how matter is cycled through ecosystems. By this point in the term, they have drawn and interpreted food chains and food webs, and are familiar with using diagrams to represent ecosystem processes. I start the lesson with a basic understanding of the atmosphere's composition and its layers before going into the Greenhouse Effect and the role that carbon dioxide plays in it. I mostly use a PowerPoint supported lecture for this, borrowing some slides and diagrams from Climate Solutions [https://www.climatesolutions.org/].

Over the years, I've learned that many student struggle with the vocabulary terms and concepts that are involved with understanding climate change. For most students, ideas such as the composition of the atmosphere, the carbon cycle, and global warming are challenging to grasp. In fact, most of my students think the atmosphere is up in the sky somewhere and global warming is caused by the ozone layer. The problem for most of them is that these things are not concrete. They are abstractions. Terms like carbon dioxide, climate change, and the greenhouse effect are just words that they're trying to organize in their mind without anything tangible to hold onto. They can't see carbon dioxide. They confuse "climate" with "weather". They struggle to relate to the time scales necessary to understand what climate is, let alone how it changes. And the notion that the atmosphere holds heat is just strange.

On top of this already shaky scientific foundation, they've heard through the media that other things are somehow related to climate change. These include, coal and oil, agriculture, hurricanes, and the Toyota Prius. Even the online textbook I use, The Habitable Planet [https://www.learner.org/courses/envsci/index.html] has a mish-mashed glossary of terms for their chapter on Climate Change: aerosol, albedo, anthropogenic, coral bleaching, deforestation, Kyoto Protocol, paleoclimate, permafrost, and sinks. It's not surprising that many of the students are confused and struggle to understand what's going on.

So I began using mind maps to help students learn these various concepts and to parse them out so they can see how they relate to each other. Because mind mapping involves the physical act of writing down words and seeing how they connect, I hoped it would help make these ideas more concrete. Doing this in small groups also helps students to discuss the ideas and challenges them to refine their understandings as they explain their ideas with each other.

Because climate change is such a large topic, I decided to simplify the lesson and focus on specific aspects of climate change. I limited the essential concepts to the following:

• Climate
  
• Weather
  
• Carbon Dioxide
  
• Carbon Cycle
  
• Terrestrial Heat
  
• Greenhouse Effect
  
• Global Warming
  
• Solar Energy
  

These concepts form the foundation of what I refer to as "basic climate science". The students begin their mind maps with these concepts and then, if we have time, I expand the lesson to include other topics that are related to climate change. These are ones they may have come across while discussing the "basic climate science", or they may have heard about in the news. As you can see some topics, such as fossil fuels for example, have subtopics associated with them as well.

• Deforestation
  
• Ocean Acidification
  
• Sea Level Rise
  
• Loss of Snow Pack/Water Supply
  
• Arctic Sea Ice
  
• Polar Bears
  
• Fossil Fuels
  
• Coal
  
• Oil
  
• Natural Gas (Methane)
  
• Extreme Weather Events
  
• Drought
  
• Hurricanes
  
• Policy Solutions
  
• Carbon Tax
  
• Cap and Trade
  
• Transportation Solutions
  
• Light Rail
  
• Buses
  
• Electric and Hybrid Cars
  
• Desertification
  
• Crop Loss/Failure and Loss of Food Security
  
• Population Growth
  
• Emergent Diseases
  

The setup for the activity is very simple. In order to make the mind maps, the students only need a large piece of butcher paper and writing implements (I like using crayons.) My students also use the Internet to look up terms and concepts, but they could use a textbook.

Here is a link to the handout I use for the activity: climate_change_mind_map.docx (Microsoft Word 2007 (.docx) 66kB Jul20 17)

The mind mapping activity itself is familiar to the students because they have already done similar activities in class. One such activity is called "The Ecological Footprint of Shopping." In this lesson, students take one item they own - their phone, a backpack, their socks, etc. - and on a large piece of butcher paper, they trace back all of the materials, labor, and energy it took to create this item, transport it to them, and then dispose of it. This lesson is a mind map of sorts; it's a visual representation of a vast concept - the ecological footprint. I will admit that when I first have students do "The Ecological Footprint of Shopping," I have to spend a lot time getting them to add more parts. They tend to oversimplify at first and don't think about all of the details. I face the same issue when they draw their food webs, which I have them do in small groups. They focus on only a few species at first and don't consider all of the possible interactions. However, in both of these lessons, they begin to enjoy the idea that concepts can be interrelated. Consequently, by the time we get to climate change around week seven, the students are familiar with the basics of mind mapping even though I've never explicitly labeled it as such.

Working in small groups, they begin by writing down the terms from the handout and reviewing the definitions, either from my lecture notes, the online text or via Google search. They then start to draw the lines connecting the concepts and talk with each about which lines go where. It is important that I walk around the room and check in with the students throughout the process. This helps to keep them on track and not get distracted, but it also allows me to ask them questions about their mind maps, to challenge some of the assumptions they've made and suggest other possible relationships they may not have considered.

In order to form the groups, I will often count off students in sets of five or six. The number of groups depends on the activity and the number of students in the class. For this exercise, I usually have about twenty-four students and so I'll have six groups of four. Everyone gets a number between one and six and then they get together with students in the same group. I start this practice during the first week of class and so students are used to it by now. At first they're annoyed, but by the end of the term, they've accepted it, and in the process they've had the chance to work with most of the class, not just the folks they sit with. Of course, on some days I let them work with their friends. This decision is most often based on how I'm feeling and how the class is doing overall.

I don't grade the mind maps, but I do evaluate them openly with the students. I'm looking for how well they can explain the relationships between the topics. In particular, if I ask them a question about a specific relationship; can they explain the logic behind it? Because the mind map represents the students' understanding of the concepts, it's important to realize that there is not a single "correct mind map." Some students will find valid relationships in unexpected ways and are able to clearly explain their reasoning. However, it is necessary to point out mistakes that they make in their mind maps. These most often occur when they have either made a relationship that doesn't exist or is tenuous at best, or when they have missed a relationship.

The activity usually lasts between thirty and forty-five minutes, depending on the group. At the end of the activity, I ask the students to get up in front of the class and explain their work in a short two-minute presentation. This gives other students the opportunity to see what their classmates have done so they can learn from each other. It also gives the presenting students practice in communicating their work and ideas in public. I don't grade them on their presentation, but I will question them in front of the class about their mind map, again to give them practice in debate and discussion in a public arena.

I usually do the activity in the middle of the week and so I often have another lecture afterwards in which we can review what they learned and they can ask questions. If there is time, I have them read Casualties of Climate Change [https://www.scientificamerican.com/article/casualties-of-climate-change/)]and watch the video A Sea Change [http://www.seattletimes.com/video/2650204511001/sea-change-the-pacifics-perilous-turn/] about ocean acidification and its effects on the Pacific Northwest. The students are then quizzed on the material the following week and then it shows up again on final exam. I don't ask them to recreate their mind map on the quiz or the exam, though I do give them the option of explaining their answers using drawings or sentences.

In the future, I would like to have the students start the mind maps on their own as a homework assignment so they can come to class with the definitions and a basic idea of the relationships. I hope this would allow us to spend more time discussing the mind maps and I wouldn't have to review the topics as much during the activity.

For a review of the theory behind mind mapping, check out:
[http://www.mindmapping.com/theory-behind-mind-maps.php]

I think it's important to start this lesson with an explanation of the "basic science of climate change", which I think of as covering the composition of the atmosphere, the greenhouse effect and how it is impacted by the carbon cycle. This gives the students a grounding in the science so they can then explore the various topics without losing touch with the science.

During the activity, you want to check in with students to make sure they have a good working knowledge of these topics and ideas and correct any misconceptions that arise. This can be done during the final presentation of their maps, but it's usually better to talk to the students while they are working in their small groups; that way, they don't feel embarrassed when you correct them in front of the class. Still, it's nearly impossible to check everyone's work before they present their maps to the rest of class and I often find myself calling out a group in front of the class. When this happens, I find that it's an opportunity for me to review one of the topics and clarify it for the whole class because most likely other students have the same misconception.

I have now used this activity in two different classes and assessed its effectiveness the second time I used it. In both classes, I lectured on the basics of climate change science and then students performed the mind mapping activity during their lab. Then, the following week, they were quizzed on their comprehension of climate change science. Specifically, I asked them to explain how the burning of fossil fuels leads to an increase in the temperature of the earth's atmosphere. This was an 8-point question on the quiz and I considered a student "at level" if (s)he scored 7 or 8 on the question.

In the second class, 71% of students were able to answer the question "at level" (I don't have data for the first class.) This was lower than I was hoping for, but still not awful. I think some students got confused with all of the various concepts. When I did the mind mapping exercise, I did not focus first on the "basic climate change mind map", covering the fundamentals of climate change science before adding other concepts, such as deforestation, extreme weather events, and mass transit. The next time I do this, I will start with the fundamentals first before delving into the other parts.