Analyzing Student Data in a Spreadsheet

I this sheet, you'll find collected the test data from a range of rather famous students. I have attempted to make some sense of it all.
First, the raw data after sorting by average.

And here's the students' improvement in test scores shown in a chart. 

It's interesting to see that all the students' test scores have improved. Whatever the teacher is doing, he/she might want to continue that. Except for Katherine, all the scores show a steadily improvement. Some students lose a point or 2 at some point, only to regain them in later tests. Katherine is the exception. Katherine scores remarkably high on test 8. She also shows the highest total improvement over the last 5 tests.
All in all, there doesn't seem to be a clear pattern in the improvement of the students. Some students show very little improvement overall.

So far, this is my least favorite of the Google tools. I'm fairly proficient with Microsoft Excel and thought that I could crank this out pretty quick and easy. Not so. Many shortcuts that I use in Excel don't seem to be a part of Google sheets. Sheets are slower and less user friendly than Excel. I guess I'll be uploading from Excel until Google improves the sheets.