The format of my computer lab is this: Students come in and sit on the floor, looking at a projection of my laptop on a large screen. I give them about a 15-20 minute lesson, which includes instruction and modeling of what they will be doing that day. Then they go to their individual computers and work on what I showed them.
One limitation to this method is that they don't all walk through the steps together with me on their own computers, instead they get all the information up front. Therefore, I have to be careful not to overload my lessons with too much information, otherwise they may get confused.
Despite that limitation, I really like having the lab setup this way. It has worked great for the past 2 years, and I have a pretty good sense of what a "digestible" lesson looks like.
But Scratch can become so complex that it really needs to be presented in a highly structured manner, or else the students can easily become lost.
That's my challenge. How would you begin?