Instruction to the teachers
- Initiate a discussion by asking the following type of questions:
i) How do plants prepare food?
ii) How do the plants use the food prepared by them?
- Explain how the food prepared by the plants that is stored as starch can be detected using a test.
- Ask the children to do this activity in groups of 3.
- Let them crush an apple or a potato in water.
- Then, ask them to filter it using a filter paper, and collect the filtrate in a test tube.
- Ask them to add a drop of iodine to the filtrate and record their observation.
- Let them repeat this activity with the remaining food stuff.
- Initiate another discussion by asking the following type of questions:
i) What changes did you observe in each case?
ii) List the food stuffs in which the change was observed.
- Explain to them that wherever a colour change was observed, i.e. the filtrate turned blue, it indicated the presence of starch on that food stuff.
Follow - up activities
- Ask them to find out which food nutrient is starch.
- Tell the students that there are tests to detect the presence of other food nutrients like fats and proteins too.