Sounds like fun! One thing that I have learned with little kids, is that most activities or crafts that you think will take them at least 30 minutes to do, they may rush through in 5 minutes. Some kids will take their time and really get into it, but most kids won't. So, I would have lots of additional ideas to help fill the time. I do the arts and crafts at my church's VBS every year and I have found that the kid's really enjoy what I call - Big, Messy Art day. We go outside and do several tactile and messy activities. This would be good for even the younger ones. I also include some science type activities. SteveSpanglerScience.com has great experiments that you can do, mostly with stuff you already have at home. Some examples of things I have done are: quicksand(cornstarch and water in a pan, fun to play with), finger painting(cover an area or table with butcher paper and put globs of tempera paint for them to play in - also add shaving cream (not menthol) to the mix and this makes it more fun and helps with the clean up), watered down paint in squirt bottles, scented paint(made from koolaid), mentos and coke experiment(see stevespanglerscience.com). You could do this in their bathing suits and then just hose them down when you are done. Have fun!