Prepare a cabbage juice solution by boiling red cabbage in water. Allow the juice to cool. Strain the solution. Add vinegar to the cabbage juice. Note any colour change.
Tea also serves as a good chemical indicator.
Carrot, beet, and blueberry juices also act as indicators. Determine over what range each operates. Place several pieces of dry ice in another beaker. Pour the sodium hydroxide solution into the dry ice, then continue pouring it back and forth between beakers. The solution undergoes continuous colour changes while this is taking place.