By the way my nephew's teacher said he started the school year with a Bang and was ready for 3rd grade, he told her, that his aunt had made him a work book to study while on summer vacation and that's why he was ready =D.
in case you want to know how to created the book, its simple there are so many Free resources on line for work sheets. I printed grade appropriate work and had them velobound in a book. My co-workers thought I was being mean , because I was making my nephews work during their summer break, but I think it was valuable learning time that we were able to take advantage of. So I really recommend this it helps them a lot. I included fun work sheets like coloring ages and puzzles, connect the dots and drawings to make the work fun. I even included their picture and a special message to make it more personal, They loved their books and I loved the results.