I don’t know whether our school currently reports semester or year grades but I do know that they have used both these methods in recent years. So not all schools report the same way.
@3girls3cats, when a student misses a day, it is presumed that they should have already done the work due on the first day they got ill. It’s due the day they return. This was apparently what happened to the OP’s son. No, they don’t expect a student out the week with flu to be working the entire time. And since the assignment was to annotate, I think the OP’s son was also stretching it to expect that “annotation in his head” would be ok. He could have contacted the teacher when he was doing the assignment before he got sick. He could have contacted the teacher the day he was ill. He could have contacted classmates and asked them whether the teacher expected written notes to be turned in that day. Asking what the assigment is 2-3 days after he should have completed the work is sure to leave a bad impression. He missed his chance to present his work orally. I’m not sure why he thought the teacher would not expect written notes.