Rulers mean warning and punishment, and rulers have the principle of scale and standard. Isn't this what life needs in the process of growing up? Without rules, it is difficult to make a square. Isn't the ruler a wake-up call for our lives?
Using a ruler is an educational method, not a tool and purpose to beat children. Putting a ruler at home is to let children know the ideas and laws. Of course, using it once in a while is not enough. Let children know that there can be no ruler, no "ring", no "ruler" and even no principles and rules. This is a solemn and serious life truth.