Wood, sunshine and solar ovens
Answers are for parents and teachers.
1
Write what “reflect”, “absorb” and “trap heat” mean and give one material for each.
Reflect: bounce light (foil). Absorb: take in light and turn it into heat (black paper). Trap heat: keep heat in (clear plastic wrap).
2
Two cups of water start at 20 °C. After 20 minutes cup A is at 32 °C and cup B at 26 °C. Find the rise of each. Which cup was better?
A: 32 − 20 = 12 °C. B: 26 − 20 = 6 °C. Cup A was better.
3
Draw a village where the trees are gone. Show two problems that deforestation causes.
Answers differ, for example: animals without homes, soil washed away, long walks for wood.
4
Why do many families in Egypt put a solar water heater on the roof? Give two reasons.
Egypt has many sunny days; sunshine is free, renewable and clean (any two).
5
Write your own improvement for a solar oven that stayed cool. Say which part you would change and why.
Answers differ, for example: add a clear cover to trap heat, or line the box with foil to reflect more light.