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.
2015
1933
1965
1980
1936
1970
2008
1995
2006
1963
1977
2009
1938
2019
2011
2010
1973
1990
1976