Can Students Be Held Accountable for Online Lecture Material?

In an asynchronous online class, I have an assignment in which students are to answer a question based only on assigned course material. They have a few weeks to complete the assignment. They have to cite course material throughout their answers, including specific page or lecture slide numbers. I don’t tell them which specific course material is covered, as this is something they should be able to figure out if they have been attending to assigned readings and assigned online lectures.

There is one particularly key slide in an online lecture that provides the most relevant information to answer the assigned question. The text of the powerpoint slide itself is not very helpful in answering the assigned question - you have to actually watch the lecture to get the important info. Anyone who paid attention to that lecture slide should do very well on this assignment.

I was disheartened to see that so many students either 1) did not cite the lecture at all or 2) cited the correct lecture slide but in a way that missed the key points because they just summarized the text of the slide rather than the much more important and relevant verbal material from the lecture.

Is it too much to hold students accountable for material stated in a particular lecture slide? I want to think it is okay to have a good chunk of their grade on this assignment based on the verbal lecture. But even most students whom the LMS shows “watched” the entire lecture didn’t apply this material at all in their answer.

I’m trying my best to beat AI - and this assignment definitely did that - and I also want students to do better work overall, which did not happen on this assignment. Any of your opinions are appreciated.