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.
2003
1967
1992
2007
1909
1969
2005
1960
2010
1975
1950
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1891
2011
1921
2014
1896
1940