Can I sue the school for slander?

my son was in school and told this girl that she dropped her pencil. The teacher told him that that was ual harrment and called him a pervert, she told my son that she knew he was just trying to get this girl to bend over. She also gave him 3 days detention. My son upset went on to the next cl. This teachers next cl came in and the teacher told this whole cl what a pervert my son was. (A boy from this cl came up to my son after school and told him the teacher called him a pervert) I went to the principle and he just said that he was standing behind his teacher, he didn't even want to know what the boys name was that was in the cl after my son. All he said was that the teacher did not say this and as far as he was concerned it was over. My son never asked this girl to bend over or to hand him the pencil all he said to the girl was that she had dropped her pencil. What I want to know is can I sue the school for slander?