Peel a clementine or an orange. Light a candle and let it burn a little. Take a piece of the peel and squeeze the yellow on the peelagainst the flame of the heating light.
What can you see? Which fruit creates the most fireworks?
It is not only air in an orange peel, but there are also oils in the peel that you use when, for example. makes perfume. When you squeeze the peel against the flame, you release the oils in the shell that are ignited by the flame.
The idea comes from Louise Alfredsson at Nätraby School in Nätraby via www.lektion.se