The Caffeine Catastrophe formative assessment (FA) asks students to explain why caffeine consumption can be lethal to one person but not to another. This FA targets benefits-costs-risks thinking. The FA focuses on the relationship between toxicity and chemical quantities with a specific emphasis on lethal dose. In this FA, students will think about the connections between ratios of chemicals in a chemical reaction and toxicity as well as how to conceptualize measurement of chemicals on both molecular and macroscopic levels.
In the FA task, students use the 
Caffeine Catastrophe Worksheet to guide their activity. The worksheet begins with a brief story about three teachers going out for coffee and an image of the relative size of the three teachers. After multiple coffees and two five hour energy shots Mrs. C becomes ill and eventually dies from caffeine overdose. The students use this information and the diagram of the relative size of the teachers to answer the questions in the worksheet.
This FA task was tested with 11th grade chemistry students in a school focused on STEM disciplines. In the class in which it was tested, the students had recently been studying chemical reactions, through the lens of toxins and their reactions in the body. In advance of the FA, students analyzed patterns among toxic chemical reactions and equations to categorize the four main types of reactions (combination, decomposition, single replacement, double replacement.) This FA is intended to connect the topics of chemical reactions and chemical quantities, specifically the mole concept.
Examples of student work
Question 1: How is it possible that everyone drank the same amount but only Ms. C died?
Becca - Ms. C died because her body couldn’t handle that much energy and every person body are different
Justin - Each person weighs different so that amount can affect the person that weighs less.
Naomi - Ms. C’s immune system is not strong enough and she might have a fast metabolism.
Teaching reflections:
It is interesting that students are focusing on the body and the body’s ability to process a toxin. Becca’s thinking seems to indicate that different bodies can handle different amounts, which is similar to Justn’s idea about different body weight and how it handles a toxin. Naomi’s thinking connects to her prior knowledge around the immune system and how it handles illness, but also mentions the metabolism and implications for the way a body processes chemicals.
There is also seems to be an interesting association between caffeine and energy. Energy is a very vague term, especially used here.
Follow Ups:
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I would be interested to ask Naomi more about what she means about metabolism: she is the only student who is thinking about chemical reactions in the body, whether she realizes it or not.
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For Becca’s response, I would ask her what the differences between the 3 teachers are, to get a better sense about “every body is different.” It is unclear if she means toxin/ caffeine tolerance differs from person to person, or if it is dependent on the size or form of the body.
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I would ask Becca what she means about energy as well. Where did she get the term energy from? What does she mean by it? What does it mean to be “unable to handle energy”- what does that look like for Ms. C?
Question 2: Show the amount of caffeine in each person’s body by using dots to represent caffeine molecules.
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Becca |
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Justin |
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Naomi |
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Teaching reflections:
In general, the three students seem to show a higher concentration of caffeine molecules in Ms. C, the smaller teacher.
However, there is little record of student thinking since there is no written explanation.
This question / diagram has a lot of potential to show how students are thinking about the amount of caffeine in the 3 teachers bodies. I would change the prompt to dig a little deeper into how students are thinking. I might add a question like “Explain your diagram”: or more specific ones like “Explain the differences /placements of caffeine molecules in each of the teacher’s bodies in your drawings”.
The FA could also be redesigned to have a larger focus on modeling. For example, students could use the same body models to explain why Ms. C died and the other teachers did not.
Students could also be prompted to use the models to explain the caffeine concentration changes in question 3.
Question 3: Do you think Ms. C would have survived if she didn’t drink both of those 5-hour energy shots? Why or why not?
Becca - Yes she would have survive. She wouldn’t have that much energy and substances in 5 hour energy and her body would do pretty well job in maintaining her alive.
Justin - Yes! B/c she would’ve survived since the coffee would have been enough energy
Naomi - I think she would of survived because she only had one.
Teaching reflections:
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All the students think that Ms. C would have survived without the 5-hour energy shots.
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Becca brings up the idea of energy again- this time she seems to say that the contents of the 5 hour energy would overwhelm her body’s ability to maintain itself.
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It’s not entirely clear what Naomi means- does she mean Ms.C would survive IF she only had 1 five hour energy?
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Justin also discusses energy- that the coffee would have been enough. But enough for what?
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It might be worthwhile to change the prompt from mentioning 5-hour energy. Perhaps the teachers could have espresso shots, which have a higher amount of caffeine than coffee. Or they could take packets of powdered caffeine. The term energy is a more colloquial term that distracts from the focus of the quantity of caffeine.
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It might also be helpful to add a question like: If Ms. Chodkowski had only 1 shot of caffeine, would she survive? Explain why or why not. This question would allude more to the idea of caffeine quantity versus “energy”.
Question 4: What do you think happened in Ms. C’s body that caused her to die?
Becca - The substances build up in her body taking over her immune system and there wasn’t enough white blood cell to control it.
Justin - All that caffeine and energy makes your heart beat very fast and jumpy.
Naomi - Too much caffeine in her body, she couldn’t handle it. She overdosed.
Teaching reflections:
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Similar to Naomi’s response to the first question, Becca brings up the idea of the immune system reacting with toxins in the body. I wonder what substances she believes are building up in the body. I would be interested in asking her how she imagines the white blood cells “control” the substances.
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Justin brings up the effects of caffeine on the body. I would be interested in how he thinks these effects are caused in the body, and why it did not do the same effects to the other teachers.
Question 5: The caffeine was toxic to Ms. C which resulted in her death, but it was not toxic to Mr. K and Mr. A – they were fine. How can something be toxic and not toxic at the same time?
Becca - It depends on the amount of white blood cell the person has and how strong their immune system is.
Justin - It would depend on how much your body can take and everyone is different.
Naomi - They were not harmed because their body could handle the caffeine because they have a stronger amune system
Teaching reflections:
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All students mentioned the idea that the amount of a chemical substance makes something toxic.
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I wonder why Naomi thinks the other teachers have a stronger immune system- I would follow up and ask her about that.
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Justin seems to be repeating a similar idea that he brought up for the first question. I would ask him how he sees that everyone is different. I would also ask him what controls what your body can “take”.
Question 6: People drink caffeine and coffee all the time, but it still killed Ms. C. However, if people drank hydrochloric acid, which is toxic, they would certainly get sick and die. What makes one substance more toxic than another? Explain your thinking?
Becca - It depends on the amount of white blood cell the person has and how strong their immune system is.
Justin - Depends on the ingredients. There’s substance that is just toxic. Others that depends on the amount you take.
Naomi - The more toxic substance kills a person way faster then the less toxic one. Less toxic substance kills a person slowly. The elements used in a substance makes it more toxic than another because the elements used always matter and changes the danger of that substance.
Teaching reflections:
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Becca returns to the idea of white blood cells. I think I would ask her about how she thinks wbc’s take care of toxins. I might ask her how WBC’s act around caffeine and how they interact around hydrochloric acid.
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Naomi has a very complex and interesting response about differing toxicities. She seems to make the connection that the elements in a substance have an effect on the danger of that substance. It seems that she is starting to hint at the reactivity of toxins in the body. I would follow up with her about what she means that “elements… change the danger of a substance.”
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If I were to change this question, I might ask students to make a specific comparison between hydrochloric acid and caffeine to get them thinking about the different effects and reactions the two substances have on the body.