When he was a boy, Jack assumed everyone saw the world the way he did. He thought it was natural to have to strain his eyes to see the chalkboard at the front of the classroom. But then one day when he was in fourth grade, he tried on his friend’s new glasses and was amazed: he could see clearly for the first time! He realized that he needed glasses too. What he thought was normal vision really wasn’t. He didn’t have to go through life squinting!