that's what I was thinking as well. I'm only 22 now, and I remember that even at age 13 I had only just begun puberty. Even if the boy had hit puberty at 11 he'd still be in the middle of it and displaying few secondary sexual characteristics.
IMO this would qualify as pedophilia, but I'm not that well versed on the definitions other than a person who is attracted sexually to children lacking secondary sexual characteristics and acts on it. In this case, the woman abused her position of power and violated the trust given her by the school, the community, and the boy's parents.
She should have gotten 10 years plus, IMO, equivalent to what a male teacher acting on a female student would have received in such a situation.
-- edit
And, yes, rape and sexual abuse can occur even if a victim is physically aroused. Whether the boy was aroused or not had nothing to do with his capacity for or actual willingness to participate.