This is a great classroom management system to use in the classroom.
You can teach your students to raise their hands by the hand signals (also uses some sign language) that represent:
This management system helps teachers identify what students want to say in the classroom. For example, if you are looking for an answer to your question, you should call on students who display an "a" hand signal, and if you see student has their hand up with a "c" hand signal for a comment, you know not to call on them.
I use this in my classroom and it is very successful!