Choose something uniform (like small marbles or coins) and have the students weigh ten.

The tables were white marble, small and round, just big enough to seat three.

It looked like a small, gray, slightly deformed marble.

In the center of the circular well hung a small blue marble representing Earth.

His eyes were small gray marbles bright with intelligence.

Thus the smaller marble will go faster if you apply the same impulse of momentum to each body.

Those from larger fish can be more than half an inch wide, about the size of small marbles.

The Hungarian's eyes were hard, like small black marbles.

It contained four round pills, about the size of small marbles.

Each was the size of a small marble.