How do lenses in glasses and telescopes bend light to help us see?

Light bends in lenses because it changes speed when it passes from air into glass or plastic. A curved lens steers rays so they meet in the right place. Glasses correct where your eye focuses the picture; telescopes collect more light and shape it into a view your eye can use.

The lovely shared trick is focus. In glasses, the meeting point needs to land on the retina at the back of the eye. In a telescope, a large front lens gathers faint starlight first, then a smaller lens enlarges that tiny image for looking.