Here's a neat idea for the first day of school. Write a letter to be delivered later. You can write to your child or they can write to themselves. This free mini lesson guides you through the process:
Letters to the Future: http://www.teacherspayteachers.com/Product/FREE-Letters-to-the-Future-179923
If you want to you can even send the letter by email at some later date.
FutureMe.org will even send the letter by email