��Chen Gaomu

(a)

Many teachers mentioned 95+8+7104-8+6112-16+5, similar to the three questions like this, how the abacus teaching?

The three questions in the teaching of abacus and mental arithmetic can be carried out:

Ninety-five

Eight

Seven

one by one

It can use the "difference" and "complement" more convenient.

Dial 95, plus 8, 8 difference 3, 3 dial, dial to 5, getting 1, 103, plus 7, 7 Complement 3, dial to 3, into 1, 110.

One hundred and four

-8

Six

one by one

This problem can be used to "fill" hundred teaching than convenient.

First, students should make clear the concept of "compensation", ten hundred up 9, a close 10, this number is a few hundred patch number.  Such as "8" is "92 hundred up".

104-8, dial 104, minus 8, 8 up hundred is 92, set aside to 100 on the 1, 92, 96. Plus 6, dial 6 is the difference of 1, set aside to 5, into 1, 102.

One hundred and twelve

-16

Five

one by one

Dial 112, minus 16, dial to 100 on the 1, plus 16 up 96 hundred 84. Add 5, dial 5, get into 1, and get 101.

Try it! Some teachers teach this way, and the effect is better.

"Complement, make up the numbers, the difference", the three concepts are very important. When the students are good at distinguishing them, when should they use a certain concept?

It is helpful to use mathematical terms and try to use mathematical terms as far as possible. If some metaphors are used, they can be translated into mathematical terms as much as possible. (two)

A teacher asked: my children like to play abacus, can not get rid of the abacus for mental calculation, how to do? Can you do the calculation without an abacus?

This is a good question. Abacus abacus aims in mind, can not always rely on the abacus abacus ", is to use abacus". Therefore, in the course of teaching, it is necessary to practice the calculation of mimic beads.

Recently, a named "image", is the abacus abacus re innovation. Their practice is:

1, recognize the number of teaching, so that students can use repeatedly remember like beads, beads pictures or computer moving plate for students to remember the number of beads like that.

2. Through the demonstration of multimedia courseware, how the image of the brain in the brain is performed, the calculation process of dynamic motion is established in the brain. As long as the addition and subtraction of mental arithmetic is less than 20, the calculation of multiple numbers can be adapted and assimilated.

3, the image in the brain directly simulate the abacus completely, reduce the direct calculation of abacus beads link, the effect is very obvious, especially suitable for the popularity of abacus teaching.

(three)

The abacus is very good, and the ability to calculate is not up, how do you do it?

Abacus abacus abacus is material alone, abacus abacus mental abacus, to put the material into the mental abacus abacus, is the real abacus! Just stay in the abacus level, not timely get rid of abacus, even on the abacus psychological dependence, it is impossible to form the abacus! "Abacus" as the name suggests, the abacus is the foundation, is the target of mental arithmetic. The abacus is an intermediary, is a bridge, the abacus in mind, the formation of abacus in mind, the key is to simulate the beads in training on the basis of the abacus (several beads and beads to the number of translation translation before training), usually called "empty". Empty dial can promote the brain "bead like" the formation and use of "Pearl like" mental arithmetic, which is called "abacus". Generally speaking, it is called "the brain in the abacus."

There are many forms of vacant training, usually there are "far disk and empty dial" and "close to the disk". "Out of the air", that is, the distance is far away from the abacus, the empty hand dial is also larger. "Dial", which is nearly blank from the abacus is close, empty simulation beads, small amplitude. The "near disk" is also divided into "imitation dial" and "micro dial". When "imitating the dial", the amplitude of the dialing beads is not much larger than the dial time difference. When "small dial", the size of the dialing beads is small and small, and most students with strong mental calculation ability are the form of "small dial". We observed that children with mentally retarded children or mentally retarded children usually had a large range of air dialing. Children with higher intelligence level had a smaller range of air idle time, and some could hardly see the presence of empty dialing. We observed that these children jittered with hand - held pencils, or blinked their eyes in mental calculations, in fact, by other forces.

In a word, "empty" is the key to dial the abacus, if less practiced or not practicing "empty dial, will lead to excessive dependence on the abacus, forming" set ", negative thinking is very difficult to make children's mental arithmetic ability can be improved.

(four)

Abacus teaching is from high up, and the primary school mathematics is from low. The abacus should not learn from the low count?

There are usually several methods of calculation, calculation, calculation, calculating arithmetic, estimation etc.. These algorithms "mental arithmetic, mental arithmetic, quick" is from the peak date, from high to low were calculated, primary school mathematics textbooks in the "manual" is from the low count, this is just an example for. The new curriculum standard, advocate "calculation method", therefore, diversification in primary school math teaching in the teaching of writing from the low count at the same time, should also try from high up, because no matter from high up or low from the date, the calculation rules they are the same, namely "digital alignment, the number on the same digital phase subtraction. The standard sum of over ten, a move into a standard, not a forward subtraction, a back ten subtraction". This method