I think this activity looks like fun, but it really would not work in an orchestra classroom. (And I'm pretty sure my junior high students would not want to hold each other's hands). I thought of a revised version of this game that I played with my class today to get their brains focused and to get them to concentrate. It was super easy to do and the students really enjoyed the challenge.
I wrote on the board four commands: STAND UP SIT DOWN
CLAP HANDS STOMP FEET
I then told the students they must repeat my command and do what I say. That was very easy, of course. Next, I had students say the opposite of what I say, and do the opposite of what I say. (I told them that sitting down was oppposite of standing up, and clapping hands was opposite of stomping feet) Again, students had no troubles doing this and they felt very smart. Time to make it hard!
The next command was for students to say what I say, but do the opposite. That was tricky, but many students were able to get it. The last command was for students to say the opposite of what I say, but do what I say. That was the hardest one. It really messes with your brain.
Anyway...I just thought you might enjoy this little activity to get your class energized and focused.