Think of the sources you read to explore your topic (articles, books, films, videos, images, or websites) as different threads in a conversation. Just like blog comments, each source expresses different ideas, observations, discoveries, or interpretations of the historical problem or question you choose to address.
As you read your sources, try to figure out how they relate to each other:
Do they agree;
Do they contradict each other;
Do they help you understand your issue from a different perspective?
So when you read your sources, think about the story they're telling you and about what they each have to say about that story.
By actively reading your sources as if you're participating in an interesting, complex discussion, when you write your paper, you'll be able to demonstrate to your teacher that you have a deeper understanding of your topic.
Image from Hobbs, Renee. "New Approaches to Information Literacy." ACRL's New Information Literacy Standards, 30 Mar. 2015, http://www.slideshare.net/reneehobbs/acrls-new-information-literacy-standards.