I use sign language in my classroom as a form of communication. This started yeas ago as a means for me to communicate with a student that only spoke Russian. I saw the benefits of being able to "converse" with him. He was able to "tell me" when he needed to go to the bathroom, if he wanted some water and if he felt sick. This was so important for the both of us. The other children in the class were very interested in the special way we "spoke" to each other and wanted to learn.

Some of the signs that I use in my classroom are:
yes, no, sit down, please, thank you, bathroom, water, red, orange, yellow, green, blue, purple, brown, black, white, pink, stop, walk, and I'm angry. The sign for I'm angry allows the students to express their feelings to each other if needed. Sometimes when working in small groups they might take something from each other or say things that they should not. This gives children a way to express their emotions when they don't have the words.

I have attended workshops and have researched this on the Graduate level. I have read about the benefits and have seen them first hand. This is what some of the research reveals:
Sign language is a 2 sided brain activity that increases brain function
Raises communication awareness
Enhances children's vocabulary
Can create higher IQ levels in children
Enhances reading skills
Enhances fine motor coordination

The above reasons are just a couple of the many benefits for children that use sign language. In the classroom it also has many benefits:
Lower's noise levels within the classroom
Reduces need for Teacher to raise their voice
Children pay better attention, they have to see you
Provides children the ability to express emotions