Changes of state

Today we discussed Changes of State, specifically, solid to liquid, liquid to solid, liquid to gas, gas to liquid, and solid to gas.
Concepts boiling point and melting point were also discussed. We will follow this lesson up with a lab prac on Ice to Water to Steam.

Science

During science we have been learning about liquids, solids and gases we learnt that you can compress liquids and gases but not solids. Also, that you can change the shape of gases if they are sealed in. But liquids cannot change shape as they flow. But why is it that you can the shape of some solids but not others, for example: you can change the shape of bark but you cannot change the shape of plates. or a plank of wood. Does anyone know why this is?
Does it have something to do with the molecules?