The child should be able to countersign the check, and a parent* deposits it in the parent's account.
Because it takes a couple of business days for the check to "clear" (be acknowledged by the other bank, and money transferred), the parent would then have to withdraw that much money from their own account and give it to the child.
If someone gave my child (referred to as Alice) a check like this, I'd treat it as a learning experience, and go with Alice to the bank and have her countersign the check in front of the teller.
* Actually, anybody; a countersigned check is almost as good as cash. All that's stopping a thief from stealing a check, forging a signature and depositing it in their own account is a teller verifying the countersigned signature.