Measured,1mm. Page 89 of the first volume of mathematics in the second grade of primary school is to let students experience the process of measuring the length of different objects with student ruler, meter ruler and tape measure. The measurement standard is the actual measurement, and the result is1mm. The measurement is to describe the observed phenomenon with data according to certain laws, that is, to describe things quantitatively. Measurement is the quantization process of non-quantized objects. In mechanical engineering, measurement refers to an experimental cognitive process of comparing the measured value with the standard quantity with the measuring unit, so as to determine the ratio between them.