Give him a dictionary, have him pick a word for you to spell. Spell it wrong anyway, showing him your not perfect is a good place. Then ask for another chance, don't always get it right on the second chance. This teaches him that he's not a failure if he doesn't gibs up.
God I wish for those days back sometimes, could have done way better wif muh son. Muh daughters excelled, boys are different, encouragement ain't enufs sometimes you haz to show em.