•   Clear plastic ruler
•   Cylinder shaped clear jar (e.g. a pickle jar)
•   Rubber band
•   Funnel
•   Transparent tape 

•  Remove the jar's label
•  Attach the ruler to the outside with the rubberband ; make sure the bottom edge of the ruler is even with the bottom of the jar. Or secure the ruler inside the jar so it is standing vertically with the end at the base of the jar. Tape the ruler in place so the numbers can be read from the outside of the jar.

Note: You can use a permanent marker to mark inches on clear tape and put 
it vertically to the outside of the jar beginning at the base . Cover the marks
with a piece of clear waterproof tape.

Directions for use

•   Put the funnel in the jar .
•   Put the jar out in a secure area to collect rain .
•   Read the ruler to determine how much rain was collected .
•   Empty the jar after each use.