Experiment leaders: Ela and Joe
The visits at Heritage Academy are two hours long with a half hour break in the middle. We are able to complete two experiments in that time! For our December visit, Ela and Joe led two experiments with an emphasis on energy in food. The first experiment was making a LED light up using potatoes, onions, and lemons. Ela and Joe started with a short presentation on ways energy can be stored and how it relates to batteries. The students then broke out into groups with the graduate student mentors to run the experiment. The first part of the experiment was to measure the voltage of a potato, onion, and lemon alone followed by connecting them in series. This demonstrated how voltages add together when the batteries are connected in series. The students were then given a LED bulb to light up. In order to light up the bulb multiple fruits/vegetables needed to be connected in series to achieve a high enough voltage.
During the lunch break, the graduate student mentors cleaned up the battery experiment and started setting up for the second experiment. The second experiment used soda can calorimetry of snack foods (popcorn, cashew nuts, and cheese puffs) to calculate their stored energy. Joe and Ela started with a brief presentation on calorimetry and how energy is stored in chemical bonds. Working in the same groups as the first experiment, the students assembled the calorimetry apparatus with the help of the mentors. This involved a soda can, partially filled with water, on a stand so that the snack food could be burned beneath in order to heat the water. The energy required to change the water temperature was then related to the energy (i.e. calories) in the food. The mentors helped the students with these calculations and discussed possible sources of error in the experiment. The students really enjoyed this experiment and we were happy with how safe the students were around open flame.