One of my favorite physics labs that I do in my class is making an electric motor. The students get so excited when they get their motor working (even taking selfies with it). For some of the students, it take them quite a while to finally get it to spin continuously. This year when we did it, there were several groups that wanted to leave their motors up and running all week. I love to see students gets excited about physics (and chemistry of course)!
Once they get their motor working, then I tell them to tweak it like adding more batteries, adding lights, changing the number of magnets, etc. It’s fun to see the ideas that they come up with. Then, they have to explain to me how the change affected the operation of their motor.
I teach at a 1-1 computer school. I am always looking for new ways to incorporate the computers into my lesson plans. This year I started to have students do video lab reports. This was the first lab that I tried the video lab report with. The students had to explain each part of their motor and its function. If students can explain a concept to some one else, then you really know that they have got it.