Well, hosted a webinar today and technology failed. The presenter's internet crashed...we think...so with 40 minutes left, and 60 people online, how do you pick up the pieces and move on? Key word of the day - wing it!! It took maybe 10-15 minutes for us to get the presenter back up, and more than half the folks stayed with us, so kudos to those wonderful people! Myself and my coworker filled the time with information about the software, Sketchpad, some ready-to-use lessons...clearly not the topic of the webinar, but, better than just closing down.
Go in with a back-up plan - be ready to do the lesson another way, or give the students a 10-15 minute 'group discussion topic' while you fix the problem....anything that says "yes, it's not working but we can move on and it's just no big deal".
For example, we pushed on through the webinar with a bit of humor once the presenter was able to rejoin and some grateful participants who stuck with us. Others are joining us for the retake tomorrow. It all works out one way or another, so just keep that in mind when using technology in the classroom.