Prepaid cell phones are easy to use and easy on the pocketbook. They're available without contracts, without termination fees and with low activation fees. A few are designed especially for kids and include onboard parental controls like in-and-out call screening. The units themselves are typically pretty reliable and sturdy, too. Some, like the Kajeet kid series phones, are budget friendly and sport eye popping graphics designed for the younger set. You may even be able to integrate a prepaid phone with your family plan later, though of course you'll need to make sure the phone is compatible with your current service provider.
With a prepaid cell phone there won't be any unhappy surprises at the end of the month. Once the prepaid texts or minutes have been used, the phone won't function until it receives a new infusion of cash. A pay-as-you-go approach is a bonus when your child is in the middle of cell phone training 101. After that, use your own judgment.