The correct answer to this open question is the following.
The cumulative exam for U.S history is that kind of exam that is going to include all the topics that were taught during a certain period of time. For instance, if the teacher decides to do a cumulative history exam at the end of the month, you have to study all the topics, themes, and sub-themes imparted in class during that period. For instance, if the topic is "Ancient Civilizations," you have to study the first three most important ancient cultures such as Sumeria, Egypt, and the Indus Valley civilization, with all the dates, characters, events, and details included in each lesson.