There's the inherent learning that comes just from being a child, ever curious and interested and inquisitive about the world around them, learning every day as they explore and discover through play - in the sandbox, at the park, in the ravine; digging, building, drawing, gardening; playing board games and video games and even watching television. Children are always learning just by being children.
But sometimes a little bit of forced learning is good, too, a little bit of scheduled and supervised learning time when they're sway from school.
At the beginning of every summer we go to the library and sign up for the summer reading program, in which school-age kids sign out books at their reading level, keep track of the books they read in a passport-style log book, and do a book report for the librarian after every third book read and receive a little prize. It's a great way of making sure we don't fall behind with our reading during the summer months.
We are a family of avid readers so our boys have never had to be forced to read, but every night before bed they have half an hour of quiet reading time after we tuck them in just to make sure.
And ever since they've been able to print I've kept summer journals with my boys. Twice a week we sit down with their journals and write out the highlights of their week. It's a fantastic way to keep their writing skills up during the summer, ensures their brains and imaginations are still active by the time they have to go back to school, and makes a wonderful keepsake of their childhoods!