Obviously since I do not know your child I am not able to give an accurate opinion here. However, for children with SM, without additional learning problems or severe social delays (What is your child like one on one with another child, ie, at home? Is he age appropriate? Is he able to communicate?) children with SM should not be held back. What needs to be done are accomodations within the school setting, not retaining him. If he is academically ready for the next grade level, mature and ready, then holding him back is not the correct decision. This may hurt his self esteem as well as stifle his growth. You need to talk with your school study team about this and have a professional who knows your child read over the reports and help you with this decision.