To attract attention to the student movement of the particles of a gas, ask students, "why is the gas particles do not agree to the bottom of the container.
To attract the students to see the motion of the gas particles. Then asked the audience, "Why do not fall into gas particles together in the bottom of the container.
To attract by the students look at the picture motion of particle gas, then ask the students. "Why don't agree to the gas particles together at the bottom of the container.