Kids out of school and with a lot of free time does not have to mean that they cannot use their time wisely. I try to have a schedule that includes fun things, but also includes learning and chores. It is not easy, but if you make the activities interesting the kids will love them
One of the main things I motivate my son to do is reading. Books can keep him busy for hours and will help him with his vocabulary.
I have found some summer reading programs that help us make reading fun
Barnes and Noble
Barnes and Noble offers this program where kids read 8 books, complete a reading journal and turn into the nearest B&N store and they get a free book.
Book Adventure has a program where kids search for books, they read them offline and then take a quiz and they can earn prizes for their reading success.
Scholastic has a free program that runs from May 5 to Sept 5th. The kids read books, take challenges and can earn rewards.