What you may not know is that you probably already know how to do this; the instructable will extend the instruction to show how calculating the volume of a cylinder is similar to calculating the volume of other shapes.
This instructable is part of the Burning Questions Round 6.5 contest... If you like this, please vote for me!
Step 1: Gather equipment
1. Some type of measuring device
2. A calculator (some units have a dedicated pi key, which would be handy)