Here's an example: the dilemma of teaching sewing to a couple dozen kids is that only two or three can see you demonstrate at a time. Meanwhile your back is turned to about 20 kids who have access to pins, needles, and scissors. We've all been there, it ain't pretty. Then of course throughout whatever project you're working on kids wind up spread out across seven different steps and it takes forever to get anywhere because you can't help them all at once.
Smart Board to the rescue! For each of my projects (and each of the practice steps leading up to the projects) I created short videos for each step. The entire class can watch the instruction, and I can replay it as many times as they need without losing my mind repeating myself endlessly. Then when some begin to move ahead while others move slower (or miss a few days of school), I can just play the video for the step everyone needs. It's been amazing!
An added benefit: I upload all the videos to a designated channel on YouTube, that way kids can access them at home if they are doing make-up work or just want to work on projects on their own time. Not saying I get a lot of views, but at Parent/Teacher Conferences a few weeks ago a few parents did tell me that their kids had been watching the videos at home. Hooray for useful technology!