World War II has just broken out. Adolf Hitler is trying to choke the food supply into Britain. His U-boats (untersee boats) are hunting Allied convoys travelling across the Atlantic Ocean which travel as a group trying to protect themselves. The German submarine commanders used periscopes to redirect light from above the surface down to the submarine to spot where the Allied ships were. We explored this combination of science and history with the help of some parent visitors as we made periscopes of our own.