I teach online in an adjunct capacity, but I have also taught for 5 years in a full time capacity on-ground.  I find that many of my online students try to do the tasks without doing the reading or listening to the live or recorded chats.  No matter how much I stress participation, there is always a few that do not, and then those few complain about their grades. Any advice?

Having a back up plan is great. Another use is for when you go into a classroom and the overhead or compuuter does not work.  It always helps to have a back up lecture or activity prepared.