Sweet Potatoes Three Ways: Cooking Using Conduction, Convection and Radiation

Sweet Potatoes
Credit: Feast Down East

For the past three months, I’ve worked with the fifth graders at Parkview Elementary to study North Carolina’s favorite vegetable: the sweet potato. In early October, we harvested nearly thirty pounds of sweet potatoes from a tiny school garden bed. Using our harvest, we connected sweet potatoes to the curriculum, examining weather patterns, properties of matter, and energy transfer.

North Carolina Essential Standard 5.P.3.1 is my favorite, because it basically begs teachers to cook in the classroom. The standard states: Explain the effects of the transfer of heat that occurs between objects at different temperatures (conduction, convection or radiation). I admittedly had a fourth-grade level understanding of energy transfer, but with the help of this rap song and this cooking video, I felt prepared to lead some fifth-grade level lessons on cooking with heat.

Over three weeks, we prepared sweet potatoes three ways. Below, I’ve included an overview of our recipes and lessons.

Week One:

  • Heat transfer method: conduction, heat transfer from one substance to another
  • Recipe: mashed sweet potatoes
  • Lesson: we observed the many ways heat was transferred through conduction: burner to pot, pot to sweet potatoes, and sweet potatoes to potato masher. The metal potato masher felt warm to the touch, but our plastic tasting spoons did not. Metal was therefore a better conductor of heat than plastic.

Week Two:

  • Heat transfer method: convection, heat transfer from a fluid
  • Recipe: sweet potato “fries”
  • Lesson: we compared the properties of raw sweet potato sticks to sweet potato sticks cooked in an ActiFry air fryer (side note: raw sweet potatoes are a totally acceptable food in North Carolina and they are delicious). As the sweet potatoes cooked in the ActiFry, we discussed that fluids can be gases or liquids and that convection has the ability to turn sweet potatoes that are cold, crunchy, and bright orange into fries that are hot, crispy, and deep orange.

Week Three:

  • Heat transfer method: radiation, heat transfer as waves through empty space
  • Recipe: sweet potato soufflé
  • Lesson: when microwaved, marshmallows provide the perfect example that heat expands, cold contracts (another required NC Essential Standard, 5.P.3.2). We gathered around a microwave to watch marshmallows grow for thirty seconds, and when we opened the microwave, the marshmallows shrunk to their original size. We combined the heated marshmallows with microwaved sweet potatoes, salt and cinnamon to create a sweet potato soufflé.