Here is the item again:
As her teachers had recommended, Madison tried to study in the library but
discovered that the good music, unlimited soda, and big tables at the campus
café made a great place to do homework during
fall semester, Madison must have eaten 150 pizza slices while she slogged
through Fundamentals of Biology.
The blank space between homework and during makes a fused sentence. At this spot, there are two complete sentences joined with no punctuation, causing a major error. Madison tried to study in the library ... begins one complete sentence. During fall semester, Madison must have eaten 150 pizza slices ... begins the next complete sentence.
To fix this problem, you could put a period after homework and capitalize the D for during.