Hot Stuff – Lesson 8, Extension – Using a model solar oven
This lesson requires prior building of model solar ovens in associated STEM lessons. Working in groups, students use their pizza box solar oven to cook something simple (egg, cookie etc). They then explain how it works using their knowledge from this module and evaluate their oven’s design.
Introduction: Review previous learning and introduce the learning intentions using the end of Lesson 8 of the Hot Stuff PowerPoint.
Activity: Working in their groups, students use their pizza box solar oven to cook something simple, for example an egg or a cookie.
Evaluation of solar oven and discussion: Through questioning and discussion, students evaluate the designs of the solar ovens.
Conclusion: Inform students that in the next lesson they will answer questions about what they have learnt about heat and also about whether they liked the way it was taught to them.
Students will:
- evaluate the design of their solar oven after testing it by cooking something
- use scientific concepts to help explain how the pizza box solar oven works
- Ensure students have previously designed and built their pizza box solar ovens in the associated lesson.
- To cook in the solar oven: simple items such as eggs or cookies (one per group)
- Thermometer that is capable of reading up to 100 °C or more (one per group)
- Timer (one per group)
Review the previous lesson and introduce the learning intentions using the end of Lesson 8 of the Hot Stuff PowerPoint.
Provide a brief review of the Sun, photons, phonons, and insulation as applied to the solar ovens (this would have been discussed when designing the ovens in the associated STEM lesson):
Ask students to think back to lesson 4 when they learnt about the Sun giving off huge amounts of energy in the form of photons.
- Why are photons so important? They carry the energy from the Sun to Earth; some turn into phonons which warm things up.
- Now turn to the solar ovens: when the photons strike the solar cooker they pass through the Glad Wrap cover and strike the black cardboard base. What happens to the photons when they strike the black cardboard? The photons are absorbed and turn into phonons.
- What does this cause? This heats the base. It then gives back off a large amount of infrared photons that, along with conduction, help heat the air that is trapped in the oven by the clear plastic wrap.
- What else helps the oven stay hot and heat up further? The corrugated cardboard of the pizza box; this helps to keep pizzas hot when they are transported, because the gaps makes it difficult for phonons to move through the walls.
Students should plan how to test out their oven: for example taking temperature readings as it heats up and timing how long it takes for an egg or cookie to cook.
Danger: The inside of the oven may get very hot and burn students if they touch it.
Students should write a brief report that includes the maximum temperature reached and how long it took to get to that temperature.
After cooking, students should reflect on their solar oven design in their groups:
- How well did it cook?
- Could we change our design to get more heat into our oven? How?
- Does heat escape from our oven? If so, how else could we stop this happening?
Each team reporter should share their overall experiences with the class, including how they could improve their design if they were to do this again.
Inform students that in the next lesson they will answer questions about what they have learnt about heat and also about whether they liked the way it was taught to them. In the following lesson, administer the Hot Stuff post-test (Marking Guide) and Student Attitude Questionnaire.