#8 – How to use peanuts and fire for teaching STEM (note: prepare for smoke!)

Is there something we can do to start teaching STEM in a simple way? STEM (Science, Technology, Engineering, and Math) is an increasingly popular way to teach science and math in a holistic, applied way by using the engineering design process. Teaching stem gives off the impression that it requires teachers to go well beyond their comfort zone. Thus, it appears to be a huge mountain to climb. Teachers may feel the pressure to create all new lessons, to learn computer programming, and to start making robots in their spare time. That’s not necessary at all.


We believe teaching STEM can be done by making some changes to your current teaching practice. In this blog, we demonstrate how we take a traditional cookie-cutter lab and extend it to include elements of STEM. At the end of the post, you can download our lab and the extension activities. We give you our peanut lab and So how? The peanut lab and making an effective calorimeter.


Extend beyond the lab

One approach to start teaching STEM is by extending current labs to include elements of STEM. In this case, we propose having students design and build systems that increase the efficiency or accuracy of a lab. We are not suggesting students build a better thermometer or a better metre stick (although, that would be a pretty cool STEM lab too). Rather, we are suggesting that if temperature (ie. heat transfer) is what students are measuring, then perhaps students can also design and build a system that prevents heat loss. If students are measuring the height of a building (ie. distance), then perhaps students can design a way in which students can measure the height more effectively than just using metre sticks, measuring tape, or relative distances.


What’s old is new again

Every year, my students do a lab where they burn peanuts to determine how many calories of energy per gram is in a peanut. This is not a new lab. I did a similar lab when I was a young lad back in the 80s.. And, I found a similar lab in a science textbook published back in the 90s, which I used as inspiration for the lab my students do. In our lab, students put a peanut on top of a peanut stand (which they make using a paperclip) and light it on fire. The fire heats up a small beaker of water that is suspended above the beaker. Students use the change in temperature of the water to calculate the amount of heat energy absorbed by the water which, in an ideal system, would equal to the amount of heat energy released by the peanut.


Unfortunately, the experiment is not run under ideal conditions. There are many ways in which the heat from the peanut can escape and not reach the beaker. Furthermore, there is heat loss from the inefficient transfer of heat between the beaker and the water. When students run the lab the first time, they use tin foil to create a chimney around the peanut to prevent heat loss. However, when students compare their results to the published number of calories per gram found in peanuts (thanks Google!), the student results still come up short.


Thus, we challenge students to build a system that prevents heat loss and improves their results. The challenge works in so many ways. It is open-ended. It requires students to collaborate with each other and do research beyond their own classroom learning. And, it results in students asking some interesting questions (ex. How can I produce a fully closed system? How will I light the peanut and ensure oxygen flow if the system were completely closed? What can I use to hold the water?). Most importantly, it requires students to build and test, which, I believe, is a big part of teaching STEM.


Field Notes

  • due to peanut allergies, we sometimes use potato chips too. They burn very well due to their oily nature.
  • do not use marshmallows or gummy bears. They may appear fun and interesting, but the result is a messy goo that doesn’t burn very well
  • keep the food labels for the food you burn. The students will use the Calorie information on these food labels to compare with their own experimental results.


Putting it All Together

I don’t believe teaching STEM requires a herculean change in our teaching practice. We can teach elements of STEM in our labs by focusing on the efficiency and results of the lab. Currently, we may ask students “What would you do next time to improve the results of your lab?” but not offer any follow through. Well, by teaching STEM by actually building systems that improve efficiencies, your students now can put their ideas into action. If you would like a copy of our peanut lab, please click the link below and opt in to our email list.


For the Peanut Burning Lab Handouts, Click Here


Until next time, keep it REAL.

Posted on August 31, 2017 in Activities

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