Have ‘THAT’ sex talk. honestly.
Talk to her about being presuserd into doing something to make other people happy. Tell her that chaps will say anything to get any type of sexual gratification (good god the storys they spout).
You really don’t want her getting knocked up when she hasn’t started her life and you really don’t want her getting any STDs or getting bullied into doing anything.
Boys are ruled by there hormones and whatever friends they listean to (who are also ruled by hormones).
PS
Self defence classes are a blooming good idea.