Today was a tough day

Today was the first time my 8 year old came off the bus crying. She is by far the most intelligent and brightest kid I know. She is very smart and her teacher has always been impressed by her. Well today she was crying because the "popular kids" get better grades. She is a bright girl but in response to my question of why she believed she wasn't smart she said "because the pretty girls get better grades." I asked "who told you that?" And she said "my teacher."