Science
Why do apples turn brown?
Preparation
Lesson details
- apples - purchase some apples at the supermarket
- slices of lemon
- small knife from staffroom
- apple corer
- paper plates
- paper and pencils
Lesson details
- Wash the apples under cold running water. On a flat surface with a cutting board using a knife or apple corer cut the apples into eight pieces. Set the core with the seeds aside on a plate. The students can watch you do this. Don't cut the apples up too soon as they will go brown.
- Place the students into teams of two with a Manager and Speaker. You can use team role badges from Kerrie if you like.
- Hand out two slices of apple to each team. Put the slices on the plate. Students sprinkle some lemon juice on one of the apple slices on the plate. Leave the slices on the plate for five minutes or more.
- Meanwhile on the plate with the apple core dig out some seed with your hands and place in a bowl. Pass the plate with seeds around for all the children to see. Ask them to look at the apple seeds, touch them between their fingers but not to eat them.
- Examine the two apple slices on the plate. One is probably brown by now. Explain that when you cut an apple open you release an enzyme or chemical that combines with oxygen and turns it brown. You actually tear its skin when cutting it. The acid in the lemon juice stops the apple from turning brown as fast. Have the children smell the apple slice that is not brown and write down how it smells. Ask them to eat the slice that is not brown then write down what it tastes like. Now have the Speakers share their observations with the class.