use your judgement
I think it depends on the situation. You need to ask these questions. Does your child walk to and from school? Do they take public transportation? Especially if they have after school activities. Our daughter got her cel phone when she started 6th grade at the age of 11. She was more than 6 blocks from school and it was a peace of mind knowing that if we were running late or she was then we had a way of communicating.