Do you have a good science museum anywhere near you? While it is an hour commute, I just joined the Denver Museum of Nature & Science thinking that we could use some of the exhibits as educational enrichment activities if I design some lesson plans around some of the stuff they have. For instance, you could use an exhibit like the hall of health to learn math concepts related to blood flow, etc.
I agree with what you said in your original post that it needs to be fun activities for the summer or your kids might feel like you are trying to keep them inside doing school work all summer.
