I want to get a science fair project book for my kids before the annual science fair so I can be a bit more helpful and on the ball w/ it this year. I've been looking a the series by Janice Van Cleave. Are these usually pretty interesting for the kids but easy to do. It says it uses household items that you usually have, which would be great - I spent too much on supplies for ds' project last year and now that I have two who will be doing them I want cheap.  Ds 1 is into geology-type stuff. So far all his experiments have been with rocks. They are kindergarten and 3rd grade.  Anyone have any recommendations. There seem to be a lot of science fair project books on pbs, but I only want to order 1.

TIA