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.
1980
1968
2021
2016
1987
1970
1974
1969
1965
2003
2020
1896
1975
1930
1939
2009
1986
2024
2004
2014