From making fertilizer and plastic to keeping your body healthy, acids and bases are important to a variety of areas of your life. If you are curious about what substances around your house are acids and bases, you can make an indicator from a red cabbage. An indicator changes color depending on whether it comes in contact with an acid or base. The juice from a red cabbage can indicate the following:

Color Change	What It Means
Red/Pink	Really acidic
Pinkish Purple	Slightly acidic
Dark Purple	Neutral (neither acidic or basic, like water)
Blue	Slightly basic
Green/Yellow	Really basic

Procedure

1. Chop up a head of red cabbage and put it in a bowl that can withstand heat (if you
   have too much cabbage to fit in one bowl, you can just repeat the following steps
   several times or not use the entire head).
2. Pour boiling water over the cabbage.
3. After 10 minutes, pour the mixture through a strainer into another container. I
   usually pour it into a large, glass measuring cup in the sink. The spout of the
   measuring cup then allows me to pour it into an empty 1 gallon milk jug to use for
   storage.
4. Throw away the used cabbage.
5. If you do not use the entire amount of cabbage juice and you would like to save it
   for later, put it in a sealed container in the refrigerator. If you would like to keep it
   for even longer, you can pour the liquid into ice cube trays and freeze it.