The maximum limit for a ROTH IRA contribution for a Child, under the current tax law, is $5,000, however, the contribution cannot exceed the Childs income.
I would definitely encourage the child to invest in a ROTH IRA as the amounts invested over a long period can result in potentially significant amounts in the ROTH IRA account come Age 60!
Please refer to the following link for a discussion on the potential accumulation balances of a ROTH IRA account for a child making a ROTH IRA Contributions for a few years.
http://www.asktaxguru.com/805-why-ch...ould-make.html