There's a third method, roughly in the middle of your 1 and 2. My wife practices this (she teaches Math at college level): keep the lectures at the times they a

There's a third method, roughly in the middle of your 1 and 2. My wife practices this (she teaches Math at college level): keep the lectures at the times they are regularly scheduled, but on Zoom. Use an iPad-based whiteboard (Notability) and share the screen. Allow questions, give answers. Pretty much the regular class time, only online. Quizes happen at the scheduled times. Students receive the test pages via email, and they have to print them out and send photos of their worked solutions by a certain time limit (roughly the same as the one for a normal exam, plus a few more minutes to allow for printing, etc). She simply decided to trust her students. So far she has zero reasons to believe any of them cheated; in particular one submitted an empty exam. No students have dropped the class, and the attendance is better than the one prior to the lockdown.