Drawing of a compression wave

Answer 1

Draw a series of isobar lines, making them bunch together in one part of the drawing. The area where they bunch is the compression wave, now animate the drawing to make the bunching move across the drawing.

You now have what you requested.

Answer 2

group of molecules that is squeezed together.

or

A wave propagated by means of the compression of a fluid, as a sound wave in air is.

or

a mechanical wave in which matter in the medium moves forward and backward along the direction the wave travels

Answer 3

A soundwave