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.
—
2005
1993
2021
1997
1961
1962
1964
1982
2014
1976
1994
2024
2004
1958
1984
2008