If you watch Portlandia, you may remember the episode where they jokingly said the way to have successful art is to "put a bird on it. " Sometimes I think of the same when it comes to easy art lessons and pattern. Here kiddos, put a pattern on it! While I wouldn't rely too heavily on that in my own classroom, it can work well for sub lessons. The kids may spend extra time filling in patterns.
Here is a unique set of patterns, always a good thing to have when kids get stuck. She actually has lots of sets of patterns. You will find them here on The Doodler Blog.