We learn friction via experimenting on Hammer-Hit-Needle. This is an excellent experiment to watch different gears with axles have different friction.
Feeling the friction by pulling the axle out of the gear, ranking them by the force we used; then use the experiment Hammer-Hit-Needle to verify if what we felt is exactly same or not.
The class goes smoothly and kids cooperate with each other. Team spirit is always the key to win!
