Iodine-Starch Color Switch

Mixture turns deep blue-black. Ask students to predict what will happen. Add iodine to starch solution. Key idea: Iodine forms a colored complex with starch helices. Ask: Did we make a new dye or a new interaction? Safety and cleanup: Teacher-handled dilute iodine; goggles; no ingestion. https://www.google.com/search?q=%22Iodine-Starch+Color+Switch%22+science+demonstration+experiment