Make Focused Pages for Search Engine Optimization
Separating your content into shorter pages will allow you to improve the accuracy of your page titles, and the relevancy of your page among other search results.
For example, a page titled "Resources" with a subtitle such as "Books for Anti-Discrimination Work" will not rank as highly as a page titled, "Books for Anti-Discrimination Work" on searches for any of those words.
Shorter pages will also help you get important information "above the fold."
That said, it's also true that longer content tends to rank higher in Google’s search results (Search Engine Ranking)—aim for 1000+ words of "meaty, useful content" on a single topic.