We finished the Human Body last week with the Circulatory System, I'm just a little late getting things posted. As stated before, most of my ideas this year for science have been taken from Lesson Pathways.
Habits of the Heart- lots of info, flash video and some open heart surgery video (we weren't brave enough for that one)
Another activity- Calculate stationary heart rate then compare after 30 seconds of exercise. You can have everyone compare their heart rate to each other. Then graph.