that's exactly what happened to my son (9,5) some two weeks ago.
He was attacked by some other boy in school, and instead of taking up a fight he just made some sideward movement and the attacker ran into the wall
. Big laughter from the side of my boy (he told me the story with great pride - "Mama, Tai sabaki WORKED!")
And afterwards the attacker complained to a teacher, saying that my son pushed him into the wall...but apparently the teacher did not believe him and didn't punish my son.
I think teachers generally know who is a bully and who is not.