A lens is a curved piece of clear glass or plastic used to focus light. Farsighted people have eyes that are too short from front to back. Convex lenses help eyes to focus. Concave lenses lessen the power of eyes so they can focus on things far away.
Convex lenses curve outward in the middle.
Concave lenses curve inward in the middle. Making inferences Drawing conclusions Materials Clear plastic wrap Newspaper Water Teaspoon or eyedropper Room Preparation Students need table space and elbow room. Safety Precautions None. Review concept of a lens being a clear piece of curved glass or plastic. A lens focuses a beam of light.