Testing pH of mouth at intervals of one hour.
**A .**1) Collect a strip of pH paper with a colour chart from chemistry teacher.
2) Take a small piece of the pH paper and touch it to your tongue.
3) Match the colour with the colour chart and note the pH.
4) Take some readings after having your food at lunch break.
5) Compare your readings with that of your friend.
6) Take at least 4 readings.