Poor child! I do feel for him as I was a bright child myself and it would irritate me if I saw a teacher make a mistake.
I taught in a primary sch in an area considered to have more than its fair share of social deprivation. When I first started there, If I wanted a child to run an errand, this is what wd happen:
Me: Children, we're out of blue paint. Sally, cd you pls pop next door and ask Mr B if he has any we could borrow?
Sally: (goes to next classroom, throws open the door with a bang and interrupts Mr B's lesson by calling across the room from the door). Oi! We need it blue paint!
Result was one very irritated Mr B and embarrassed Mrs Molly when Me B later complained about rude interruptions. I learned the hard way and quickly changed my style of request to this:
Me: Children, we're out of blue paint. Sally, cd you pls pop next door, knock once at the door and wait for it to be opened, then stand at the doorway and wait until Mr B is ready to listen to you. When he shows he is ready, calmly walk up to him and say quietly, "Excuse me Mr B, I'm very sorry to bother you, but Mrs Molly has asked whether you possibly might have any blue paint we could borrow?" Then Sally, say "Thank you very much, Mr B" whether he gives you the paint or not, walk calmly out of the room and use the handle to close the door so it doesn't make a noise.
The point of all this is that no decent teacher should mind being corrected, but the timing and manner it is done will make a huge difference. Give your child the right phrase to use and talk to him about timing and using quiet voice. 