Give scientific reasons :
We are able to read while sitting in the shade.

Explanation

The sun is an extended source of light which is far away from the earth. The sunlight casts a shadow of the object, in its path, on the earth. This shadow has no umbra, but penumbra which is nothing but the shade. There is a sufficient amount of light available to read in the shade. Hence, we are able to read while sitting in the shade.