Grades are the criteria used to evaluate students' performance.

We measured across the center of the wheel to find it's diameter.

Satellites orbit the earth, because they travel around it over and over again.

This plant has spheres, or globe shaped flowers!

He is evaluating something, because he is looking at it closely.

These birds are not identical, but they are approximately the same.

We did a quick calculation to make sure we had time to go to Vegas!

The telescope is an astronomical tool for looking at the stars.