Describe the three states of matter in terms of shape and volume

Shape
A gas is shapeless all other things being equal. It will, if put in a container, occupy every part of the container.

A liquid could also be thought of shapeless. If put in a container, it need not occupy the entire container. It will occupy as much as its calculated volume will permit it to occupy.

A solid will only occupy its original shape.

Volume
A gas will occupy whatever container it is put in within limits. You cannot put a 72 mols of gas in a mm^3 container without some amazing ability to apply a lot of pressure.

A liquid will occupy a volume determined by its density and mass. In general liquids cannot be compressed. 

Whatever volume a solid has to start with, it will retain that volume all other things being equal.

This is actually very hard to describe.