Starting from the correction of harmonic vibration，theoretical analysis and

experimental exploration on the sixth topic Saxon bowl of IYPT2020 are carried out. This topic

describes a fact that the ancient Saxons used the bowl with holes on bottom to tell the time. Such

a bowl sinking model can be used as a vivid case to enhance students' understanding of simple

harmonic vibration and damped vibration. In this way，the complicated formula derivation is avoided

and the simple equation is obtained. By using computer to solve the differential equation

and doing experi- ments，the feasibility of the theory is proved and the influence of some

factors on the sinking time is studied