1 Classroom
1 roll of masking tape
All the students
Each student is pretending to be an air particle. The classroom should be cleared as much as possible so that there is a lot of empty space around the middle. Tape off a section large enough for all the students to fit inside, with a bit of room to spare. The students are instructed to walk only in a straight line until they hit the tape, furniture (if the area includes desks), or a friend (if they are about to bump into a friend they should high-five instead). Upon making contact, the student changes direction and walks in a straight line until their next point of contact. Time the students moving for 20 seconds while each one counts how many times they changed direction. Get a sample of the students' number of direction changes, and repeat the exercise four more times with the following conditions:
1) Increase the size of the taped area, then repeat again after removing the tape completely and using the entire room.
2) Have some students sit out.
3) Have the remaining students walk very, very slowly.
The number of collisions is representative of the pressure in the system. Each of the conditions represents a different way to change pressure:
1) Increasing the area is like increasing the container around the system. Increasing the size lowers the pressure.
2) Changing the number of students is like changing the number of particles. Fewer particles means lower pressure.
3) Slowing down the pace is like removing energy from the system. Less energy means lower pressure.