If you want to measure how much a soil sample was damaged by acid rain you need a scale.
The pH scale is a way of describing the concentration of acid ions [H⁺(aq)] in a liquid.
Solutions of strong acids have a small pH ( 0, 1, ..), week or very diluted acids have higher ones (..,5, 6).
Alkaline solutions have pH btween 8 and 14).

What you need: Box of a music cassette as a stand for six 3-ml injection bottles (1 - 6), 1-ml syringe, 1M-HCl, pure water (for car battery), universal indicator solution (UI).
* Transfer 1.0 ml of 1 M hydrochloric acid into bottle 1 by a syringe.
* Transfer 0.9 ml of water into bottles 2 - 5.     * Remove 0.1 ml from bottle 1.
* Mix it with the water in bottle 2. Remove 0.1 ml from bottle 2.
* Mix it with the water in bottle 3. Remove 0.1 ml from bottlen 3......
* Dilute this solution another two times in the same manner.
* Add one drop of UI to each of the bottles labelled 1 - 5
Observation Photo: The different colours of this dilution series can be compared to a colour scale.
In bottles 1 - 3 (pH 1 - 3) the colour is red, in bottle 4 (pH 4) colour is yellow, in bottle 5 (pH 5) it is yellow green.