What Is What? Poem by gnrao rao

Opaque are the wood and bricks,
Transparent are the air and glass,
Air is invisible,
But can be felt.
Smoke can be seen.
Living things are
Human beings,
animals and plants,
Non-living things
are stones and rocks
and books and pencils.
Some of the things
Are man-made.
Chairs, tables, T, V sets.
Some of the things
That flow are water, milk,
and oil.
Rocks, hills, mountains
are all stationary.
The natural things
are the Sun, the moon,
water and sand.