The MIT usability team did a heuristic review of the Sakai Gradebook on 10/25/2005, based on observing one user test (we were using this initial test to list obvious problems that should be addressed before doing more testing). During the test we encountered several usability issues with the default Sakai style sheet.
One of the big issues that arose in the test was confusion around what was a link. The recommendation was to have the CSS adjusted to make the links underlined. This includes the table headers, which no one realized were clickable.
A related issue was that the 'tabs' in the OOTB template don't look like tabs. Our user interpreted them as breadcrumbs and had a lot of trouble getting from 'My Workplace' to his class. He couldn't tell if he was in his class or not. The presence of a big tab looking graphic in the upper right hand corner of the screen added to the confusion.
I've attached an image that outlines the CSS-related issues we saw in this test.
