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.
2017
1989
2024
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1950
2012
1957
1995
2020
2009
1977
1958
2015
2006
1985
2021
1965
1968