Dagwood Splits the Atom (1949)
"Dagwood Splits the Atom" was an educational "freebee" produced in 1949 by King Features Syndicate. Dagwood, with help from his wife Blondie, Mandrake the Magician, and Popeye explains atomic structure and how to create a chain reaction.
General Leslie Groves, who headed up the Manhattan Project, provides the introduction, and at the end there is a multiple choice quiz, e.g., "What is changing into helium and producing atomic energy in the sun? Protons, neutrons, hydrogen, infra-red light." Dagwood Splits the Atom was also included in Gilbert's famous U-238 Atomic Energy Lab set.