US Environmental Protection Agency
Epa: Measuring the P H of Natural Water
How acidic is your water? "In this experiment, you will measure the pH of natural water located near your home or school."
US Environmental Protection Agency
Epa: Making a Natural P H Indicator
At this site you will find a step by step process for making a natural pH indicator. One of the main materials you need to have on hand is a red cabbage.
US Environmental Protection Agency
Epa: Measuring Soil P H
This site has an experiment to find out how to measure the pH of your soil. The soil pH is an important condition that can affect the health of plants and animals.