• gas are well separated with no regular arrangement.
• liquid are close together with no regular arrangement.
• solid are tightly packed, usually in a regular pattern.

When you look at a regular outside bulb thermometer, you'll see a thin red or silver line that grows longer when it is hotter. The line goes down in cold weather.

This liquid is sometimes colored alcohol but can also be a metallic liquid called mercury. Both mercury and alcohol grow bigger when heated and smaller when cooled. Inside the glass tube of a thermometer, the liquid has no place to go but up when the temperature is hot and down when the temperature is cold.

Numbers are placed alongside the glass tube that mark the temperature when the line is at that point.

In a conductor, electric current can flow freely,

example: copper

electric current cannot flow freely

example: Most solid materials are classified as insulators because they offer very large stop the flow of electric currents 

transfer of heat between two parts of objects

example: using metal to roast marshmallows, it gets hot

sticks don't get hot

convection

takes place when heated molecules move from one place to another, taking the heat with them.

example: sun

Radiation leaves an object in the form of waves. The hotter an object, the shorter the wavelength of this radiation.

example: camp fire heat radiates toward your hands