A, accurate measurement of height: measurement of height requires “four with” 1, the same measurement time (people’s morning and evening height is different); 2, the same standard height measuring tape (measured at home, you can also be measured after a piece of paper on the wall, draw a line and then measure the height, but the ruler on the top of the head must be perpendicular to the wall, preferably with a triangle ruler); 3, the same measurer (different people may have differences in the tightness of the calipers when measuring); 4, the same standing method of the person being measured (the two feet are required to lean together, the heels, hips, back and head are against the wall, and the head against the wall must pay attention to the two eyes flat, not too much tilt. Usually, a person whose height is 2 standard deviations below the normal average height of the same race, age and gender is considered short; a person whose height is between minus 2 standard deviations and minus one standard deviation is considered short; a person whose height is between minus one standard deviation and plus one standard deviation is considered medium height; a person whose height is between plus one standard deviation and plus two standard deviations is considered tall; a person whose height is more than plus two standard deviations is considered tall. High; more than plus 2 standard deviations for the height of super high. 2. Percentile method: Those whose height is below the 3rd percentile of normal height of the same race, age and sex are considered short. It comes from the following source: 100 children of the same age are randomly selected, and they are lined up from low to high, those who are ranked before the 3rd are short, those who are ranked between the 3rd and 25th are short in height, those who are ranked between the 25th and 75th are medium in height, those who are ranked between the 75th and 97th are high, and those who are ranked after the 97th are super high. Third, the standard deviation and percentile of height for boys and girls at different ages are available in numerical tables and graphs.