Hi VANJ,
My son participated in JHU CTY last year at age 10. He loved it. Everyone is withing 1 or 2 yrs of each other, very diverse (lots of international students) and couselors help them. I was worried about my son because he can forget to zip up his pants or tie his shoes, but he was fine. I can't tell you whether it's worth the money, but it was very valuable to my DS and he's doing another jhu cty program this summer.
You can PM me if you need more info. I wouldn't over-estimate the value of programs on college resume (until they're in high school).
