Learners make their own acid-base indicator from red cabbage. They use this indicator to test substances around the house. Red cabbage juice is purple in water (neutral), pink or red in vinegar (acid), and blue or green in baking soda (base). Learners are encouraged to make acid-base indicators from other plant materials, juices, and berries. Because of the equipment involved, adult supervision is recommended. This is one of three activities in the Take Home guide for the Biochemistry unit in OMSI's Chemistry Lab. Also included in the PDF are two additional activities: Yeast Balloons and Egg Osmosis.