Sandy wants to strengthen her united states history teaching this summer. she has enrolled in a master's-level course for history majors on the underground railroad. by enrolling in the course, sandy illustrates her desire to increase her:

I believe the answer is knowledge of content

knowledge of content refers to how much a teacher understand the scope of topics that he/she expected to teach on the certain subject.

Having wider base in knowledge of Content will make a teacher much more likely to be able to guide the students in understanding a certain topic.