Having a look at why it is 'the best period'. Based on the practice of the education on Mental Arithmetic by image of Zhusuan (Abacus Mental Arithmetic) in China, it reveals that the education on Mental Arithmetic by image of Zhusuan is most suitable to be carried out
among the children of 4 to 12 years of age.

First at all, it belongs to 'the period of enlightenment' and 'the best period' in cultivating the function of the human brain. Meanwhile, a child of about 5 years begins to grow in his hand muscles and speeds up the growth at 8 or 9 years of age, when the strength being built up and the action of fingers flexible, which is just suitable for driving beads. What is more, he can leave his parents to move around freely in his daily life, and have the intellectual skill practice ~ Zhusuan relevant to such many organs as eyes, hands, mouth and brain, which, after all, is the best period of cultivating and tapping the function of the brain.

Furthermore, the education on Mental Arithmetic by image of Zhusuan belongs to the basic knowledge of calculation. During this time, children don't feel quite hard in study. If they had the education on Mental Arithmetic by image of Zhusuan in time, they are not only able to avoid the boom for knowledge in which their study will become much harder after the primary school, but lay a good foundation for the study of other subjects, especially mathematics, physics and chemistry. Therefore, it is 'the best period' to carry out the basic knowledge as well as to cultivate the function of the brain.

If this best period is subdivided, the children of 5 or 6 years in kindergarten will be superior to pupils when instructed. Because of a little study in kindergarten, they can be taught for all of their time. The teaching time is shortened, and it has no influence on the study for other things. Besides, unlike pupils, the children in kindergarten know nothing in mathematics, just a piece of white paper in the brain. They have not formed any numeral concept yet, so it is easy to teach them Zhusuan, while pupils are different. They firstly have to undergo the process from numbers to beads and from bits to place-showing sticks between written calculation and Zhusuan, and the contrast and adjustment in the calculating methods as well.

We have performed an experiment simultaneously in the teaching of Mental Arithmetic by image of Zhusuan between two groups of children (three children in kindergarten, at the age of four and a half, five and a half respectively; two pupils aged eight and nine), teaching for an hour every Sunday. It was found that the three children in kindergarten began forming 'image in brain' after 3 months. As soon as many additions and subtractions concerning two numbers were given to them, they said the answers immediately. But the two pupils in the second and third grades took half a year to make it.

Then come to the reason why it is 'a good method'. The education of Mental Arithmetic by image of Zhusuan must start by learning Zhusuan and familiarizing the abacus. By the repetitive practice of working the abacus, it will be engraved on the mind naturally. In the end, the abacus cannot be used any more and children are also capable of calculating directly according to 'the image in brain'. The abacus is suitable for the teaching features of children, because children are all fond of being curious, playing and understanding things directly. As to children who begin to learn, an abacus, as a concrete, objective and vivid calculating tool, is the aid for teaching and learning and a toy as well. While they tough it, they will find a number appears when driving a bead, and the number changes when moving it as if playing games, full of pleasure and attraction. As a result, children become very interested in study. At the same time, it is simple and vivid to express and calculate numbers by an abacus. Beads can show Numbers and digits are decided by place- showing sticks, so numbers correspond to digits with a quite clear arrangement.

As to the subtractions among additions, additions among subtractions, quivery and decimal system, and mutual transmit of multiplicative pithy formula, their principles and algorithm are so clear that children are easy to remember and learn. What is more, such actions as listening, looking, reading, moving hands, calculating, numbering off and translating numbers and beads each other as quick as lightning in the education on Mental Arithmetic by image of Zhusuan are all suitable for the aural and visual development and motion law of children, thus it is easy for them to accept.

Another feature for children is that they are fond of moving about and doing better than others are. The education on Mental Arithmetic by image of Zhusuan is different from that of general knowledge courses like Chinese, nature, geography and history, typical of the fact those teachers explain and students always listen to in a passive position at class. The exercises are usually required to be done after school is over. Zhusuan is simple to the courses like music and physical education, at which teachers instruct and students learn, acting together in an active position. Under the instruction of teachers, students read and count off numbers, or use abacus, or listen to and look at questions or answer them. Besides, the competitions can be spiced into several group to have a look at who calculates correctly and counts off rapidly, which always enables students to stay in a positive state of method of Mental arithmetic by image of Zhusuan is fit for the features of children, and inspires their enthusiasm and initiative for study. During the course of positive and active study, calculation and thinking, their brain functions have been cultivated, which makes children become much more clever and intelligent.

The practice has proved that the education on Mental Arithmetic by image of Zhusuan being carried out all over the country plays an evident role in tapping the child intelligence. In many competitions on Zhusuan skills, what famous traditional Zhusuan players of our country finished in 10 minutes could be done by those who have received the education on Mental Arithmetic by image of Zhusuan in less 5 minutes. Quite a few teachers say that children can finish in advance the whole courses of the primary school for 6 years, especially the subject of mathematics after they learn Mental Arithmetic by image of Zhusuan.

As to those in middle school, something won't be estimated now because of the lack of practice. However, it is able to be sure that the subjects of mathematics, physics and chemistry relevant to counting and calculating directly are bound to be finished in advance with the calculation speeding up. It indicated that the education on Mental Arithmetic by image of Zhusuan being carried out enables the students of the primary and middle school to complete the present study assignment in advance. In this way, some time can be saved for adding too much more new teaching materials, or these students can be made to go to college or serve for society in advance. In view of this, Zhusuan will play a significant part in developing the cultural quality of human being and promoting the progress of the society.