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American Entry Into World War II

written by: Andrew Otocka • edited by: Carly Stockwell • updated: 8/14/2013

This lesson plan is the second in a series of five on America's involvement in the second World War. It deals with the American decision to enter the war, including Axis military successes, the relationship with Great Britain, and the conflict with Japan that led to the attack on Pearl Harbor.

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    Oil producing countries map American entry into World War II was the result of a series of foreign events that swayed domestic public opinion. Primary among these events were the widespread conquests by Axis armies on three continents and the sinking of American merchant ships, which strengthened the relationship between the U.S. and Great Britain. In addition, the German invasion of the Soviet Union brought that country into the conflict, providing the U.S. with an uncertain but powerful ally when it subsequently declared war after the attack upon Pearl Harbor.

    Lesson Objectives: This lesson focuses upon the events that led to American involvement. Students should be able to explain why America ended up entering the war in late 1941.

    Materials Required

    • Either a class set of laptops or access to the school library or computer lab.
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    1. Have students color or shade in Axis conquests in both theaters of war. Students may use any available resource to learn the correct countries to shade: textbook, laptop computer, smartphone....

    2. Discuss with the class how the war was going in 1941. Who was left fighting the Germans (the British and ultimately the Soviets)? Who was left fighting the Japanese (the Chinese)?

    3. Refocus the conversation on the United States. Remind the students of the Lend-Lease program and America's strengthening relationship with England. Then talk about the toll that German submarine attacks were having upon American shipping, including the fact that American sailors were dying in these attacks.

    4. Look at the maps of global mineral and petroleum resources. Ask students what they notice about Japan in both maps, then have them compare these maps to the conquest maps referenced in step 1. The correct conclusion is that Japan lacked the natural resources to continue to expand its economy without taking them from other countries or international trade. Explain that as Japan intensified its war efforts against both China and European possessions in Asia (such as Hong Kong and Indochina), the American government refused to allow American companies to continue trading with the Japanese. This put Japan in a difficult position: either back down from its expansion program, or attack the United States.

    5. Using either classroom laptops or library computers, have students access National Geographic's site on the attack on Pearl Harbor, found at: Students should use the interactive timeline on the site to familiarize themselves with the events of December 7, 1941. To insure that they are working, cull more vocabulary words from the site and add them to the list that students will be assessed upon.


  • Map of Oil Producing Countries by Ekrub-ntyh under CC BY-SA 3.0

America's Involvement in WWII

America eventually moved away from Inclusionism to become a key player in WWII. This series of lesson plans examines America's involvement in the second world war.
  1. America's Involvement in WWII: Moving Away from Inclusionism
  2. American Entry Into World War II
  3. Diplomacy and Combat in World War II
  4. The Home Front in World War II
  5. The End of World War II and the Aftermath