Look at the sand we have from the beach (or river), using a hand lens. Note that the edges of the grains are sharp, especially the grains of sand that are quartz. So what? What kind of a difference does it make if some grains are sharp and some are rounded? Sharp grains probably blow along in the wind just as easily as rounded grains.

Look, using a hand lens, at the grains of sand that are on sandpaper. Compare the grains on heavy-grit sandpaper with those on "fine" sandpaper.

What does sandpaper have to do with sand that is blown in the wind?

What happens when we rub a piece of wood with heavy-grit sandpaper? What happens when we rub the wood with fine sandpaper?

The same things happen to rocks when wind blows grains of sand; sharp grains scratch and wear away the rocks more severely than rounded grains, and a strong wind will
accomplish the eroding of rocks more rapidly (and severely) than a mild wind.

Do you remember discussing how wind-blown sand and dirt feel against your arms and faces? If any of you have ever been in a sandstorm, you can recall your experiences and explain them to the class.

The long-time effect of wind-carried particles gradually wears down the earth's surface. It not only wears it down, it moves masses of earth and sand from one place to another.

Find pictures of wind-worn desert rock formations in magazines. In some pictures you may note that wear is greatest near the base of the rock. Why do you suppose that
is?

If possible, observe sandblasting to see how wind-driven sand is used to clean buildings or remove paint from surfaces.