1, do three things, that is, first check whether the zero scale of the scale is worn, and if it is worn, re-select a scale value as the starting point of measurement.

2. Secondly, look at the measuring range (range) of the scale. In principle, the length measurement needs a measurement. If the measuring range is smaller than the actual length, the ruler needs to be moved many times, which will lead to a large error.

3. Finally, it depends on the minimum scale value of the scale. The length value represented by the minimum scale not only reflects the different precision of the scale, but also relates to the validity of the measurement results. The measurement range and minimum calibration value should be selected according to the actual measurement requirements.

When in use

1, pay attention to correct placement and correct observation when using.

2. The key to correct placement is: the edge of the ruler is aligned with the measured object, which must be aligned and overlapped, and cannot be skewed; The facet of the ruler must be close to the measured object and cannot be "suspended".

3. The key to correct observation is that the line of sight is in front of the terminal scale line and perpendicular to the small plane, so that the number of large cells and small cells can be seen clearly.

Extended data

Scaling error:

① The causes of errors come from the accuracy of measuring instruments, the limitations of experimental principles, the objective factors of environment and people, etc. Therefore, errors in any measurement are inevitable.

(2) can only try to reduce the error, it is impossible to eliminate.

(3) Errors are different from mistakes. Errors are caused by improper methods and subjective factors (reading errors, memory errors, etc.). ), so the error should be avoided and can be avoided in the experiment.

(4) Ways to reduce errors: choose high-precision measuring instruments, improve experimental methods and master experimental skills. In general experiments, the effective way to reduce errors is to take the average of many measurements (this method is effective in reducing accidental errors).