What makes you a male/female is the difference between X & Y.  Whether or not your body produces estrogen or testosterone at the right time during embroyitic development.  Up to a certain point both males and females look exactly the same.  Once sexual development starts, the gonads either decend to create testies, or travel up inside the abdomen to become ovaries.  In females the tip of the penis forms the clitirous and the shaft of the penis (penile tissue) forms the ceiling of the vagina (technically it's between the urethra and vagina), and in males the penis develops encasing the urethra.  In females, the area of skin that the testies decend into making the scrotum in males, splits forming the labia of the vagina in females.  In females the prostate forms a layer of squishy tissue between the ceiling of the vagina and urethra, in males this devlopes into a ball-like gland between the rectum and the penis, and surrounding the urethra.  

The major difference between males and females in regards to sexual organs is the uterus, cervix, and vagina.  There are a series of glands that merge to form the uterus, cervix, and vagina in females, where as in males they shrivel up, die, and become consumed by the body.

Unless sex ed has improved significantly in the US and around the world to include modern information, I'm guessing nobody learns much of this unless they actually look it up or take a human anatomy course in college. 

The kid is 13 years old lol...

Ok, we get it. You're smart.