Presenting data on the elements that aren't subject to self-bias would bolster his case - absenteeism and failure to complete homework (as opposed to completing

Presenting data on the elements that aren't subject to self-bias would bolster his case - absenteeism and failure to complete homework (as opposed to completing homework poorly), from the list you gave. I'm not sure that he would have gotten much use out of the rest of them, as they would be self-reported in most cases and difficult to quantify in the others.