Agelica,
Yes, that was 38 yrs ago that my 9 yr old son was asking. He approached me first and I was SHOCKED when he told me that he was getting an erection. I responded that his body was changing and that was natural.
That is when he and dad started going fishing and hanging out alot together in order to have their MAN TO MAN talk ALONE.
I acquired several books from the library that showed graphic photos so that he would understand. Though scan and see how much you want him to know. Be HONEST and STRAIGHT FORWARD with him and leave that DOOR ALWAYS OPENED if he has any FUTURE questions. You might not be happy with somethings he has to say but LISTEN then show your disatifaction but DO NOT GET ANGRY because he will not share any more with you.
Also, for my boy and girl (when she started her period) I took them to planned parent hood where they have FREE condoms and explain that if your going to PLAY wirht fire you need to protection yourself not just against pregnancy but vereal diases and these stay in your system for LIFE.
My daughter seemed to be the EXPERT on SEX in mmiddle school and I was SHOCKED how uninformed her friends were that their mothers were afraid to talk to them. When were their mothers going to talk to them when they got PREGNANT ? She was a chatter box with me in everything that was going on.
Now as adults as we have our conversations they are so glad that I was sooo OPEN WITH THEM.
M. Ruiz Torres