Lack of Watersheds introduction or information

Hello,

The Earth's air and water segment in the AP Environmental Science course doesn't provide any resources or comments about watersheds. I'm stating this because the exercise on Earth's air and water asks questions about this topic. I found it confusing that it provided two queries about the topic, even though they didn't discuss anything about it (unless I'm missing something). 

I'm pointing this out because if someone was taking an exam or test and saw questions about this topic, they wouldn't know much about the topic, thus reducing the chances of getting the grade they desired. 

This is just feedback given to hopefully include watershed information in the course.

Thank you for reading this.