There are two types of learning commonly used for online classes. This google slide reviews the differences between the two. Very often there are elements of both in many online classes. Teachers will set up times when students can reach them quickly for immediate response and may provide video chats that can be recorded and archived so that all students have access to the discussion at all times. These sessions would be mandatory for synchronous classes and would not be mandatory for asynchronous classes. Also, since many synchronous classes meet weekly, there are assignments that occur asynchronously to review material covered together and to prepare students for the discussion in the next class.