Thanks for the recommendations. Here's a bit more information if that helps with which one might be best.

The classroom will have about seven girls and six boys. The girls seem have some cliques and the boys are constantly flipping from being best friends to "I'm never speaking to him again because he said my favorite TV show was not as good as his favorite show". Some kids are ADHD/ASD/gifted.

An easy to implement and inexpensive program would be best.