I'm with Grellbunt, I would be absolutely incandescent at this.
Firstly because the girls are missing out, being disadvantaged academically and effectively punished for the boys' bad behaviour.
Second, because it smacks of victim-blaming - what possible message can the girls, and for that matter the boys, take from this if not that it's the girls' "fault" this happens and that they are the ones who need to adjust their behaviour? And it's also teaching the girls to blame themselves for any abuse they suffer in future.
Third, it does absolutely nothing to stop the boys' bad behaviour - they get business as usual, are not required to change and if anything will just learn to blame the victim.
Fourth, it does nothing whatsoever to address the wider problem. I doubt very much that whatever the girls are being taught will actually give them any real protection against predatory behaviour, but even if it did, what about all the other girls and women these boys will interact with in the rest of their lives? While the boys have just been left to do as they wish, or worse, taken on the message that the girls are to blame and potentially that girls/women who don't behave or respond to them in certain ways that they've been taught are even more deserving of abuse (that they are "sluts" or "asking for it" if they don't do/wear/say the right things).
The only thing that may be worth checking is whether they planned some separate sessions for the boys after the ones for girls (but then why not do them at the same time?); but then I'd still like to know what was being said to each group. Other than that though I'd be going ballistic!