I wrote my own lesson to achieve the same purpose. This was it:
My kids have a problem with getting to class on time. They wander in five, ten, and fifteen minutes after class is officially supposed to start. A few weeks ago, three girls wandered in two minutes before the class was supposed to end. It's a problem. I've started doing little things to change that: give the first ones treats, start the lesson early... but for this class I simply waited until there were ten of them and then said this:
"Because you are the first ones here, we are going to play a little game on the rest of the kids. Jay was here first so he is the leader. Every time I tap the chalkboard twice, Jay will pick a different position to sit in; maybe legs crossed, maybe leaning back in the chair...Whatever it is, copy it. Stay in that position until the next time I tap on the chalkboard and Jay changes his position. Now, try to get the other kids to conform to the same position. You can whisper to cross their legs or signal to them to copy you, but you cannot tell them about Jay, the tapping, or what you doing. If they directly ask, don't answer."
It was great. Twelve more kids came in and we started. A few weeks ago I had ask them to write down questions and I devoted this class to answering them. Everytime I started on a new question I would tap the chalkboard twice. Jay started out subtle (chin on hand, leaning back) and finally ended by sitting on the floor. It was such an obvious thing, that as soon as the other kids moved to the floor, two of the "unknowing" kids moved too, almost instantly. Most of them hesitated or laughed or questioned before moving down, and one kid looked around, asked what was going on, shrugged, and announced that he was a rebel. He then laughed and sat on the floor. I was timing it. It took 31.4 seconds for the twelve kids to give into peer pressure and conform to the other ten kids without any explanation.
I then asked each one of them why they had sat on the floor, and not one could tell me. They all shrugged and said and said something like "Because everyone was on the floor". Or "because I thought we were supposed to." One kid got creative and said he thought it was time to pray.
I then told them the lesson was on peer pressure and explained the experiment. We then read and discussed three amazing scriptures:
And that was the lesson.