• Aid: great physical teaching for teacher,thermal expansion demo
• Expansion and contraction material: let the metal ball cool naturally, and the ball can pass the ring,physical experiment tool
• Expansion and contraction experiment: at this time, the metal ball expands due to heat, so it cannot pass through the ring,professional physics experiment
• Elementary equipment: the demonstrator can be used for primary school science class and middle school physics experiment,laboratory experimental supplies
• Physics demonstration: demonstrate solid or metal thermal expansion and cold contraction phenomenon,slotted mass weights