Describe three ways that America's involvement in WWII helped people at home?

If we speak of the the benefits of World War to people at home (in USA), the only benefit was the end of the great depression. The employment as well as industrial production boomed because as a result of production of war material. This included the material used directly in war effort of U.S.A, as well as the material supplied to Allied power countries for cash and under lend-lease system.

In addition there was great improvement in methods of production and management of industries. For example as a result of such improvements introduced in response to war efforts, the time taken to build an aircraft carrier dropped from 36 months in 1941 to 15 month in 1945. The completer field of operations research (OR), also called management science, developed, as a consequence of the efforts made to improve effectiveness of the war.

A major social impact of the war was to induct women in many jobs that were earlier considered to be fit only for men. This contributed a great deal in bringing women in the main stream activities of the society outside the domestic sphere.

There were also many new technologies developed during the war which not only helped greatly during the war, but continue to benefit humanity after the war also. Great advances were made in design of aircrafts including jet aircrafts used in war.The war also stimulated invention of radar.

Petroleum industry developed many new specialized products and new processes during the war. Refining processes such as catalytic cracking and alkylation vastly improved the output of high octane aviation fuel.

The utility of development of Atom bomb during World War II is a highly debatable subject. But its contribution to development of nuclear plants is beyond any doubt.