Analyzing Student Data in a Spreadsheet

http://spreadsheets.google.com/pub?key=t9KMqpfHM-9keASYSjfkwGQ&output=html

The above spreadsheet is an examination of student scores. I took the average for each student, the average for each test, and the standard deviation for each test (numbers 6-10). The test average rose consistently between test 6 and 10. The standard deviation for each test stayed fairly consistent (between 25 and 26) despite the climb in averages, which suggests that the entire range of students remained the same, no one was getting too high above and no one was too far below. I then filtered out all of the student scores that were above the average and the scores that were below the average.

The graph represents the averages of the below the average test scores across tests 6-10. Consistent with the class average and standard deviation trends, this group of scores also consistently rose.