How come my sims keep failing university classes

Since we are talking about it, I put a seven Sims household through uni in the dorms. So I have experienced these issues, which I solved by going into super micromanage mode. I was so busy that I didn't even have time to pause.

I had two in soccer. A few in the brainiacs, but couldn't bother to keep up with those activities. Majority were mermaids so they were constantly trying to swim at the very end of the campus. Originally I had them all at different credit loads, but I quickly burnt out and made them all take the highest class loads to graduate quickly.

I was successful, and they all did well, so it is definitely possible if you are willing to put the effort in. However, I wouldn't exactly call it that fun of an experience.