Don't ruin math by asking him to read out loud. Let him finish his sentences and never make him feel rushed. Say something nice about them that is not related to speaking. ​ As a kid I felt like an idiot all the time and I thought others felt the same way. Just let him know there are so many skills out there that don't require perfect speech. I started to get over my issues when I learned people don't really think that way (Unfortunately it took me to my 20's to realize that). Good luck :)