How, using a Ripple Tank with a Signal Generator attached to the Dipper, can you find the Wavelength?

-First, get a Strobe Light -Then place a Card that's Covered with Centimetre-Squared Paper behind the Tank -Turn on that Strobe Light, and change the Frequency until the Waves 'Freeze' -Using the Squared Paper, measure the Distance that the Waves Cover, and then see how many Waves there is, and divide them Together to get an Average Wavelength