<ul>
<li><p>Some courses have 2 sections with different different class lengths such that one has 3 classes each week with 60 mins, and other section has 2 classes with 90 mins. What is the reason for that? I guess they cover exactly the same material?</p></li>
<li><p>What is the significance of waitlists? Why would it be that one section has vacancy and other is already full with 5 people already waitlisted? (both sections by the same instructor)</p></li>
</ul>
<p>for your second question, maybe that class just fit into people’s schedules better (while there was a class conflict with the other) and they may be hoping to get off the waitlist during the adjustment period/ first couple weeks</p>
<p>-The total amount of hours per week then would add up to 3. Since some sections they’re only 2 days a week, they make up for the loss of one day by adding half an hour to each section. That’s my guess. This way, you still cover the same material in the same total amount of time.</p>
<p>-It could be that some people don’t want the early morning class, so they all try to sign up for the later class, making the later class fill up first and then waitlist. Or the reverse–a late 6pm class is unpopular. And milkTea’s explanation as well.</p>
<p>Also someone may have other classes that conflict with the open section times, making the full sections the only ones they can attend.</p>