Mostly sport and exercise. Getting fresh air and plenty of exercise is the best. Next comes walking to the shops with a parent or caregiver and discussing what is around you on the way. House door numbers help with counting, car registration number plates help with letter recognition. Standing watching something working is also useful, e.g, the car wash. With older ones, a game of words, to keep them up to speed with reading. This summer, in Granny's summer school, my eldest granddaughter and I are doing (1) art - we have borrowed books from the library and we take it in turns to copy the example pictures in the books, (2) maths - downloadable free worksheets from the net, (3) computer work, using the mouse, drawing, colouring and writing words. Later in the summer, this will include taking photographs (by her, with a simple point and click camera), downloading them to the computer and creating a "book" of pictures and words.