Both of my kiddos brought home calendars or packets of suggestions to keep their brains fresh over summer break. I have also purchased different activity books for their next grade level. I have found that my 3rd grade boy is slightly standoffish about anything that resembles school work so far, but they have only been out of school for a week, and he doesn't realize that the conversations we have with him are structured to get him to think. We try to have a real relationship with our kids and have fun as a family and it is then easy to slip little tidbits of information and ideas into our daily activities.