A young boy learns about his heart through the step-by-step construction of a simple circulatory system. He learns how his heart pumps, what blood and blood vessels do, how they do it, and some of the ways to help his heart stay healthy.
1998
1969
2022
2003
1965
1966
1967
2021
2016
2024
2013
1961
1922
1956
1996