I have read that when school starts in the fall that teachers spend a good month or so trying to get the children back to where they were academically when the school year ended. What can you do this summer to ensure that your children are on track when the school year starts.
1) Make your children read every day. If they are new readers, make them read to you. Model the behavior for them. At my house we all sit down and have some quiet reading time everyday. Mostly I do this for my own sanity and to stop the otherwise non-stop chatter.
2) Play board games. Most games require reading, counting, and addition of some kind. Monopoly, Scrabble, the kids won’t even know that they are using educational skills.
3) Take some educational field trips. Make time for the museums that you might ordinarily not go to. Most children are fascinated by art museums. A fun thing to do is a scavenger hunt at a museum. Stop by the gift shop and pick out a few postcards depicting items in the museum. Then go find them. This should excite even the most reluctant museum go-er.
4) Keep a family journal about your summer vacation. Not only will it encourage your children to write about the things that they are doing, it might also inspire them (and you!) to be more creative in your activities, to think outside of the box, and look at things in a new way.
5) Study your family tree. Have the kids make up a list of questions to ask Grandma the next time she calls. Or better yet, go to visit the elderly memebers of your family with a video camera in hand to capture the stories. Some of them might not be that interesting to the children right now, but one day they will cherish those memories. I know that my own parents stories of living during the Depression fascinate me now in a way that I could not appreciate when I was younger.
6) Your backyard is a big science experiment just waiting to be discovered. Give the kids some containers and a magnifying glass and set them loose.

