Maintenance and Precautions: 1. Hanging the dynamometer vertically when in use, and adjust it through the upper thread so that the indicator points to the "0" scale line. 2. Put the dynamometer flat in the box after use, and don't be squeezed by heavy objects. 3. Wipe clean the plastic cylinder and overflow cup of the plastic bucket after use. Cultivate Learning Ability: Cultivate learning ability to lay a foundations for children to learn mathematics, physics and chemistry in the future. Mainly used in middle school physics teaching, to explore the relationship between buoyancy and the object's boiled water. Interesting Experiment: The experimental assembly is simple, the experimental effect is novel and interesting, and the experimental ability is improved. Operate Step: Use a dynamometer to weigh out any object to be measured. Calculate its mass, then immerse it in the overflow cup, weigh the liquid discharged from the overflow cup with a dynamometer to calculate the volume V, which is the volume of the measured object (any irregular shape is acceptable). Explore Physical Phenomena: Can stimulate children's interest, practical ability, exploration spirits, imagination, analytical ability, etc. Complete tools, you can operate it yourself, suitable for DIY enthusiasts.