True, at least in most places. There's also been some reports of patrons getting "adult sized" kid's meals in some places when using a DDP adult credit to order one, but this varies by location, server, phase of the moon, and whatnot.
From a dollars and cents standpoint, if the 11-year-old really wants a kid's meal (and not an adult-sized portion), you're probably best off paying for that out-of-pocket and using the credit elsewhere, schedule permitting.