Billions-of-cicadas-to-swarm-East-CoastThese lovable critters emerge from the ground in 13- or 17-year cycles, capitalizing on the power of prime numbers to keep away from predators with periodic population cycles and other cicada broods.  Here’s a cool interactive cicada map you can play with. 

Cicadas remind me of the white noise machine I used to have on my bedside table – and not because they sound alike.  As I would fall asleep, I would inevitably begin focusing on the repetition in the “babbling brook” sound pattern - the machine just played back a loop about 30 seconds in duration.

I always thought it would be a better use of the machine’s memory to store two shorter loops and play them together.  For example, a 13-second and a 17-second loop would get you 221 seconds (13x17) of noise before repeating.  

Ask your students: If you’re limited to 30 seconds of memory, are 17 and 13 the best choices for noise loop lengths?  See who comes up with the idea of non-integer loops…