The little boy in the front row squinted intently at the teacher through thick glasses. He could barely see.
In the row next to him, a little girl did not look at the teacher at all. But she listened better than the others. She strained all her senses to learn. She could not see at all. The rest of· the kids in the class have normal sight.
You might expect the little boy and girl with visual trouble to find it impossible to compete in a classroom of boys and girls who can see the blackboard and every gesture the teacher makes.