The use of basic speach, or words/terms that a person will understand.
Teacher: The volume of a container with a gas, when reduced by one half, will double the force exerted by the gas by a factor of two
Student: Uh, I don't understand. Can you give that in layman's terms?
Teacher: When you squeeze a balloon to half it's size, it is harder to squeeze right? This is because the pressure is doubled. Get it?
Student: Uh, Yah!