Iodine indicator can be purchased from scientific supply houses as Lugol's solution. Lugol's solution can be prepared by dissolving 10 g of potassium iodide in 100 mL of distilled water. Then add 5 g of iodine crystals and mix. Store the solution in brown dropper bottles. Tincture of iodine obtained from a drugstore may also be used as an indicator.
Iodine stains hands and clothes and is toxic.
Have students wear goggles and follow safety precautions when using iodine indicator. Put on gloves. Pull the steel wool pad into two halves, hold them over a piece of paper, and rub them together so that the iron filings fall onto the paper. Carefully pour the iron filings into a dry jar. Cover until ready to use.