Here are a couple of things that you could do to keep your child's mind occupied during the summer months, as well as helping them have fun learning.
Have your child write a report on one certain type of wildlife. It can be squirrels, one type of bird, deer, alligators or crocodiles (depending on where you live), one type of bear, one type of wild cat, or any other wild animal, but make it one that is native to your area to make it more interesting for the child.
Buy an inexpensive digital camera for each child. While they are writing their report, have them take pictures of the animal they are researching. If their camera has a zoom, have them take close up pictures. If it's safe, and you can find some, you could let the child take pictures of the animals in their natural habitat. If it's not safe, then you could take them to a zoo or other setting where they could take pictures. Florida has alligator farms that would be perfect.
Or, you could have the child write a report and take pictures of one of your current pets. This could include the species of pet, breed, size, name, when you got the pet, what it likes to eat, any treats it prefers, favorite toys, favorite games, favorite things it likes (belly rubbing, ear rubbing, sleeping next to who, etc). And have the child include several pictures of the pet, both by itself, and intermingling with the family.
Call around and find a local farm or ranch and schedule a day that you could bring your child to visit and learn about farm/ranch living. Make it a nice outside day so that your child can go with the farmer/rancher and learn about the animals and caring for them, also about the crops grown and caring for them, what crops are grown when and where. And also let the farmer's wife teach them a little about farm cooking and eating.
Have the child make a report on your state. Have him include state birds, trees, flowers, and any other state things. Also, the state's crops. Animals native to your state. Have them include interesting places to see in your state; beaches, parks, mountains, zoos, theme parks, old or interesting towns/villages, anything else interesting to see. Also have them include a map of your state. The report should not include financial reports, political reports, or anything else like this. They will learn about those in school. But this report would get them interested in learning more and more about their state, thereby gettng them interested for when they do learn about it in school.
You could create a "subject bowl". In it you would put pieces of paper each with a state, a president, a country, an animal, an important person of the world, and any other subject you could come up with. Any subjects that your child would be interested in would be appropriate to include, but NOT subjects that your child would not be or become interested in. Remember this is supposed to be learning, but also FUN. Put all the pieces folded up in the bowl.
Once a week have each child pull out a piece of paper and have that be his subject for the week. Remember to have the child replace the paper in the bowl to be reused.
All or each of these would keep any child occupied and keep them interested in learning. Plus most of them would be an excellent family project too!