Analyzing Student Data in a Spreadsheet

We had the assignment to take the below average students from the second-half of tests and make a spreadsheet and a chart out of the information. We were also asked to analyze and look at any trends developing. I have had experience with spreadsheets before, excel to be exact, but it had been a while. It proved that I needed practice because it took me longer than what it should have. 

After taking a look at the chart it seems to me that the below average students are improving; it might be at a slower pace than the others but they are moving up. There's one student that stands out. And if it weren't for the chart I probably wouldn't have noticed it. Katherine had a huge improvement in test seven but then plunged in test eight. I would have a talk with this student and figure out why the big plunge.