In this unit, you studied the causes and effects World War II. What do you think were the three biggest global effects of the war? Why? Do you think another world war could ever take place again? Why or why not?

I can't really help with several of these questions because they are all subjective, but I can answer the first one.

Following World War I, the League of Nations was established to aid in the maintenance of peace and the resolution of international disputes. After WWII, the United Nations was in the same boat. There were also the peace accords that brought the conflicts to a close. (You'll have to evaluate whether these were successful or not.)

the two atomic bombs dropped on japan in 1945 killed and maimed hundreds of thousands of people, and their effects are still being felt today. the uranium bomb detonated over hiroshima on 6 august 1945 had an explosive yield equal to 15,000 tonnes of tnt.