Jesse absolutely refuses to let Gary Fulcher see his drawing.
When Gary asks to see Jesse's drawing, Jesse covers it with his arm to block the other boy from seeing it. Gary persists, however; he tries to yank Jesse's arm away and even pulls on his thumb to uncover the drawing.
Jesse reacts by covering it with both arms and slamming his heel down on Gary's toe. The teacher then tells them both to be quiet and threatens Jess with the loss of recess and copying the dictionary if he makes another sound.
Jesse is very protective of his drawings. He's not comfortable with the other people at school seeing them, even though he wants to show them to his dad earlier in the novel. He decides not to because his dad sees art as a waste of time. Jesse also mentions that his teachers don't like his art and see it as a waste of supplies.