We started one during the Kindergarten year - partly to try and prove to ourselves I think that we needed to homeschool - and so that we could get a head start on "collecting things" should we ever be questioned on what DS6 "did" with his time. We have a big wall calendar where he gets to write the initials of the book and the chapter he completed. I think just writing it down helsp to motivate him and makes him feel like he acheived something. Now that we are homeschooling for real - I guess we will keep the print outs that the library gives us - showing us which books are due - and we'll know what he read and didn't read that way. I started that last school year too to keep track of what I had and hadn't read to him.
