Fossil Fuels and Greenhouse Gases
8th grade Science
Background: Students will have previously learned about ecosystems, food webs, climate, and biomes and come into this lesson with at least a basic understanding that climates, biomes, and ecosystems are related. In addition, students will have some exposure to the idea that humans can manipulate nature by obtaining materials, modifying genetics, and deriving energy sources. Ideally, the preceding topics will include sources that humans use for energy. In this prerequisite lesson, students will have been exposed to terms such as natural gas, gasoline, crude oil, and coal.
Objective: Students will be able to recall that living organisms are comprised of lipids, protein, nucleic acids, and carbohydrates and that the main constituents of these molecules are carbon and hydrogen. Students will be able to describe the process by which dead organisms turn into structures of carbon and hydrogen. Students will be able to describe the expected outcome of combustion as carbon dioxide. (45 minute lesson)
Estimated Time: 45 minutes
Essential Questions: Why are fossil fuels called “fossil” fuels? How do fossils turn into fuel? What happens when we burn fossil fuel?
Knowledge Objectives: Students should know: the 4 different biological macromolecules, carbohydrates are reduced carbon sources, compression and heat over geologic time scales leads to hydrocarbon formation, hydrocarbons are extracted by drilling or fracking, fossil fuels are combined with oxygen when burned, the more reduced the starting material, the better it burns
Materials: Laptop, projectors, PowerPoint, student lab notebooks, fossil fuels worksheet
“Fossil Fuels 101” on YouTube – https:// www.youtube.com/watch?v=zaXBVYr9Ij0
“The Making of Crude Oil” on YouTube – https://www.youtube.com/watch?v=PiBmXC8w0jg
Vocabulary (already discussed): Coal, Oil, Natural gas, Hydrocarbon, Combustion
Prerequisite knowledge/skills: Students will know the definition of coal, oil, natural gas, hydrocarbon, and combustion. Students will have already been exposed to biomacromolecules and their importance.
1.) Do Now: Match picture of object to its corresponding biomacromolecule (picture of steak (protein), bread (carbohydrate), DNA (nucleic acid), butter (lipid)).
2.) Add notes title and page number to notebook table of contents
3.) Stick page down in notebook
4.) Students will most likely struggle to recall the 4 types of bio-macromolecules without a prompt – as a result, the image will also include the 4 possible answers akin to a multiple-choice format.
- If students still do not remember after a short time, the answer can simply be given.
5.) Students will then be shown an example image of the molecular structure of carbohydrates with all carbon and hydrogen atoms notated and asked to identify the atom in the image. Students will then be asked which two atoms are the majority constituents of each image.
- If students struggle to name the atoms, remind them they can use the periodic table to find the full names of the atom’s chemical symbol.
- Leave the carbohydrate molecule up on the board somewhere for later in the lesson.
6.) Prompt students with the question: “What happens to all of these molecules when an organism dies?”
7.) Show YouTube video “Fossil Fuels 101” (which can be found at https:// www.youtube.com/watch?v=zaXBVYr9Ij0). This video does an adequate job explaining the origin of fossil fuels but does not give sufficient video demonstration for how living matter can be compressed and heated to form oil, coal, or gas. In addition, the video explains some extraneous information about the economic and political ramifications of fossil fuel. In combination with the video “The Making of Crude Oil” (which can be found at: https://www.youtube.com/watch?v=PiBmXC8w0jg), the students will be given an audiovisual demonstration of the processes involved in making fossil fuels.
8.) Provide students with out-of-order images (plants -> buried dead plants -> cap rock formation -> pressure+heat+water -> oil). There will be blanks next to each image prompting students to arrange them.
- Students will be given the correct order on the powerpoint slide, so they simply need to pay attention to the lecture to correctly order the images.
9.) Compare an image of a carbohydrate molecule left on the board with a quickly drawn aliphatic oil molecule. Point out that there is NO carbon bonded to oxygen in the oil molecule and that this is very important.
10.) Prompt students with the question: “What happens when we burn oil?” (1 minute)
11.) Show students simple combustion reaction ( Oil + Oxygen -> Carbon Dioxide + Water) and have students copy the equation and 4 bullet points below it to their notebooks: (10 minutes)
- When we burn anything, we are adding oxygen to the molecule
- When there is no oxygen in the starting material, we can add a lot of oxygen, so it burns stronger
- This is why we use oil for our engines: there is no oxygen at all
- Carbon Dioxide is a harmful gas for our planet
Summative assessment activity: Students are given a prompt: “In your own life experience, which do you think is better for the environment? Coal, Gas, or Oil? Explain!” And be expected to write 3-4 sentences. With more time, students would separate into groups of 3 with each person supporting a different fossil fuel. Then, students would be asked to discuss the pros and cons of each fossil fuel with each other.