While growing up whether she is a teenager or what ever age it’s not considered good to talk to ones mother about sex and to let her know you are sex smart because it’s not the done thing. Unless you share an exceptional relationship with her, refrain from telling your mother because:
(a) Don’t know how your mom will react.
(b) Might get grounded.
(c) For information sake its ok but doing practical sex is not accepted in Islam.
(d) Let innocence embrace you and time will tell you the realities of sex.
(e) Stop being sex smart it leaves a bad impression on the other person.
(f) Sexual information might make you try it out also.
(g) Peer influence might take you on the wrong track of sexual information.
 (h) Its considered unjust but boy teenager can slightly show off their sexual smartness to their father that also if they have a friendly relationship with him, otherwise it’s better to remain silent, and never show off your sexual smartness with your mom it might back fire with you even if you are her son.