there was a craze when I was in primary school of bringing in frog spawn and watching it develop into a frog. Never happened of course, but the trying went on consistently year after year.
I have happy memories of being in primary school and collecting frog spawn for school. The tadpoles would then be released back to where it had been collected from - I'm not sure what the point of this excercise was but it was done annually by the school (in the late eighties). No mention of law breaking!