From the K-12 ideas section, many appropriate for K-5. Math projects are good because they require a minimum of materials
Lots of ideas from the K-12 list...many very appropriate for grade 5 and relevant to kids who like computers
Lots of ideas from the K-12 list, some of them followons to the Lawrence Berkeley Hall of Science Night...many very appropriate for K-5.
Metrologic
Power a super-bright LED from a low-voltage battery with a few bits of wire and a toroid core
Explore this weblog deeply for all sorts of year-round ideas, science fair included.
