This place has some great science and history ideas for the third grade. These could be edited to work with a higher or lower grade. Third Grade Thinkers: Science: Earth Cycles Need to make sure its accurate to prevent misconceptions!
Interactive Science Notebook Activities for the Human Body- each body system is represented with 31 activities and an additional 12 title pages and KWL charts. Directions, pictures of real products, and answer keys included.
human body- complete list of ideas and printables from our study of the body--This looks amazing. She did it with a four year old girl, so it may take till Clark is 5 before he has the attention span though.