A week after you placed the seeds in the various liquids, measure each sprout in centimeters. If your seeds haven't sprouted yet, sit tight and begin measuring them at two weeks. You'll need to record the length (in centimeters) of each sprout in every cup. You can make it easier to measure the sprouts by removing each one, placing it on a paper towel, and measuring its length with a metric ruler. Once you've measured every sprout, you'll need to figure out the average length of the sprouts in each liquid.