How will you distinguish between a convex and a concave lens without touching them?

(N/A) To distinguish between a convex and a concave lens without touching them,hold the lens close to a page of a book and observe the printed letters through it.
$1$. If the letters appear enlarged (magnified),the lens is a convex lens.
$2$. If the letters appear diminished (smaller),the lens is a concave lens.
This happens because a convex lens acts as a magnifying glass when held close to an object,whereas a concave lens always forms a virtual,erect,and diminished image.