Help with an excuse for skipping?

I was wondering if anyone could help me out. For one week I have missed my first period cl and have shown up to my third period cl a total of2 times, however I have continually shown up to my fourth period cl. I skipped these periods in order to work on that cles culminating project as well as skipping a test scheduled for Friday the previous week can anybody come up with a reasonable excuse. Thank you I really appreciate this .