12.
People can joke around like "she is 3 going on 13" though, meaning that she is so big and thinks she knows everything.
Anyone between 12-15
when he tolled to
over thirteen
Thirteen.
"I am thirteen years old."
I would Say Thirteen or Fourteen.
Yes you can just be cautious not to over do it. The only time this should be used is after or before workouts at the age of thirteen
absolutely.
Yes, but don't go too far.
She's 19, so no
Only if the parents would approve of it.
The plural form of thirteen year-old is thirteen year-olds.