Swimming Pool Chlorination

When you own an outdoor swimming pool, in the spring you need to "shock" it, which means add a large amount of chlorine, in order to kill all the backteria and algea that accumulated over the fall/winter/spring. But chlorine is expensive, so you don't want to add too much (and waste it). In order to figure out how much to add, you need to figure out the volume of your pool, since the label on the chlorine tells you how much to add per litre of water.

Assume your pool is a circular pool - 25 feet across and 4 feet deep. You want to find the volume of the water in the pool, and then figure out how much chlorine to add, if the label on the box says: 1 scoop of chlorine per 10,000L of water.

Here the students should be able to convert from feet to m or cm, then change that to L. Also they need to know how to find volume of a cylinder, and finally use ratios to calculate the number of scoops of chlorine. All this I had to do this spring (and every spring) in order to enjoy my pool all summer long.