[lawn]

How do you stop offline students from cheating then?

You can't have exams for everything - for example creating or extending a big project is best examined by labs and/or a bigger project. If you have the same lab series for everyone students can simply copy the solution from other students or ask someone for "help" where the help consists of explaining exactly what to do. I know I've been guilty of helping my friends a bit too much.

Organize groups? Some students may coast on the skills of others. We had a programming project assignment where I wrote 95-100% of all code. In the beginning we split it around 50/50 but it ended up with me writing it all anyways. In another course we wrote a game in Java where my friend rougly wrote 1-2 classes or something. I know it's unfair, but I didn't really care - I like to code and I didn't really have to put in any effort anyways.

Cheating may be easier in online courses, but trying die hard to stop all kinds of cheating is bound to fail, cause it's impossible.