Children carried out an experiment to investigate the presence of starch in a number of items using iodine.
They discovered that starch reacts with iodine to produce a blue or blue-black colour. It can therefore be used as an ‘indicator’, i.e. to test if starch is present in something.
Starch is a carbohydrate. It is found in plants. Green plants make carbohydrates through photosynthesis. Starch is therefore in many foods, but also in other things as well, e.g. some paper. Starch is a white powder.