Hi, why would a 4 year old lose focus when teachers ask him about things like shapes or letters of the alphabet and become unresponsive at times? thx

Many things: Any person performs at their best when they have had adequate restorative sleep, good nutrition, are healthy and in a comfortable setting. Without a thorough review of these & other factors it is hard to speculate on why a kid will not respond to a specific teacher or task. Most cultures don't do sit down schooling until age 6 because most kids aren't ready.