Explain what solids such as glass , wax and clay have in common.
They are "amorphous" solids. What this means is that they do not actually take on any particular form but they can be shaped into various and useful forms by humans, very convenient!
Some people used to claim that glass was a liquid due to the appearance of old glass panes appearing thicker at the bottom but this was actually a matter of the way they were manufactured, not due to flow over an extended period of time.
So all of them exhibit plasticity though they do so in different conditions having to do with temperature or, as in the case of clay, also having to do with the level of water present in it.