Donna makes a good point. A simple way to put it is this. Be aware of any changes in his academic performance. He may need to be taught some new learning strategies and skills. Memorization and concentration skills will be important.

A simple trick is for him to sit at the front of the class. This will minimize both the visual and auditory distractions from the other students. A simple note to the school with the request supported by his pediatrician will help.

Concussion does not usually cause a loss in IQ but will more likely cause a divergence between IQ and cognitive and memory functions. At his young age, his IQ is still developing so any loss of cognitive and memory functions will be critical. Noting the level of these skills will give you a base line.

My best to you.