A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?

Hint: When someone suffers from an eye defect, they find it difficult to read and write. There are many defects of the eye. The main few defects of the eye are- Myopia, Hypermetropia, and Presbyopia. These defects arise when the image is not formed at the retina.

Complete answer:
A student is having difficulty reading the blackboard while sitting in the last row. This means that he Is not able to see the distant object clearly. From this, we can conclude that the child is suffering from myopia.
Myopia- Myopia also known as nearsightedness is a defect in which a person can see the near object clearly but have difficulty in seeing the far object causing blurred vision.
In myopia, an image is formed before the retina. This defect can be corrected by using a concave lens which helps in forming images at the retina.
Myopia can be corrected by using a concave lens so that parallel rays coming from distant objects diverge to form an image at the retina. As it is shown in the below figure


Note:
Hypermetropia- Hypermetropia also known as farsightedness is a defect in which a person can see far objects clearly but have difficulty in seeing nearby objects. In hypermetropia, an image is formed or focused behind the retina. This defect can be corrected by using a convex lens. Presbyopia is also known as long-sightedness is a defect in which the elasticity of the lens loses. This defect mainly occurs in middle and old-aged people.