Counselor here. I said this in the Cosby thread, and it applies to an extent here too:
"Sexual abuse is not a problem that is best solved through punishment. Like so many other cruelties, it must be solved through education. Teaching our kids the value of consent from the earliest age, removing long standing stigmas surrounding sex and sexuality, becoming a society where 'good touch, bad touch' and the 'bathing suit area' are as common knowledge as 1+1=2."
The difference in this case is that she's an attractive teacher giving attention to a student who probably desires it... that makes things extremely complicated. This contact seems to have been consensual, so the child is likely to defend their abuser even though the relationship was evidently illegal and sexually exploitative.
More paranoia isn't the solution (male teachers are already incredibly rare due to the fact that even the most trivial allegations can destroy one's life, it would be stupid to extend that fear to females as well when we should be working to eliminate it), and it's well documented that prohibiting physical contact does more harm than good, but I'm not sure you can stop two people who are attracted to each other from having sex.
I will clarify this though: Cases like this are extremely rare, and the number of sexually predatory teachers is not dramatically higher than sexually predatory lawyers, businessmen, clergy, etc. Sometimes, tragedies are just aberrations that could not have been prevented.