6th grade. Just because there is no after school program offer and we both work and couldn't pick them up. Kids got my beat up old iphone, so that I could track them using "Find My Iphone" and control what messages they would send and receive. Never had a problem with overage or any texting issues. If they start messing with me or give me attitude I just lock their phone remotely! If they are not home, and I see that they are at a friend house, I just start the "find my Iphone" function and it beep so loud they can't ignore it!

Worked for us.