Each type of Earth systems literacy then defines the concepts students should understand upon graduation from high school.

He couldn't pretend to understand the processes at work upon and around him.

I began to understand that strangely human look in his eyes, those deep lines upon his care- worn face.

He knew without a doubt that Cramer understood the effect of this revelation upon him.

Now they were beginning to understand the ways of Earthmen upon Earth.

He understood well the reliance upon reason and logic that guided his daughter.

Not so much bodily exertion, you understand, as the strain upon the mind.

You merely have to understand the limits of the planet and the pressures upon it.

Today we begin our journey to the extremities of this world, and to understand the life upon it.

It imposed a kind of understanding upon the fiber of oneself.