**ABACUS TECHNIQUE**

Last class we learn how to count, add. and subtract by using our 10 fingers. But that was up to 99. For bigger number we will use Abacus.

**WHAT IS ABACUS**

ABACUS is a first man made calculator. ABACUS comes from a Greek word ABAX, means sand. In ancient time people used to count by putting marks on the sand and from this concept ABACUS has been invented. ABACUS is termed as the Father of computer.

**CHARACTERISTICS OF ABACUS**

- The abacus is made of a wooden frame.
- The shape of the Abacus is Rectangular.
- The Abacus is divided into two parts. Upper part is called “Upper Deck” and the lower part is called “Lower deck”.
- The line divided the abacus into two parts is called “Answer Line”.
- There are 13 Columns in it, in each column there are 5 beads. In the upper part each column has only one bead, this is called upper bead and in the lower part each column has 4 beads, this are called lower beads.

**BASIC RULES OF USING ABACUS**

There are some basic rules which you have to know and remember before using abacus. The rules are as follows:

- Need to make the abacus zero before starting any calculation.
- Must hold the abacus with left hand.
- Always must hold the pencil.

**HOW TO MOVE THE BEADS OF THE ABACUS**

There are some rules to move the beads of the abacus.

Lower Deck

- To move up for addition, use right hand’s thumb finger.
- To move down for subtraction, use right hand’s index finger.

Upper Deck

- For adding and subtracting use only right hand’s middle finger.

**BEADS MOVEMENT PRACTICE**

Tell your child to move up the lower beads of each column with their Thumb Finger. Now they will move down the lower beads of each column with their Index Finger. Make them practice 4 to 5 times. Now for upper deck move down the beads with Middle Finger and move up the beads with Middle Finger.

**HOW TO MAKE ABACUS “0”**

Before starting any calculation in the abacus, we need to make it zero position “0” position means upper beads will be in the upper portion of the abacus and lower beads will be in the lower portion of the abacus. For that we will hold our abacus with our two hands then lift it up on the air & after that put it on the table. Now we will see that the green beads are in the lower portion of the abacus and upper beads are also touching the answer line. Then we will sweep our index finger left to right to move the red beads up. Now the answer line is empty. This is zero position.

**HOLDING PENCIL**

Right-Handed students will hold the pencil in their right hand while doing calculation by abacus.

Lefty students will hold the pencil in their left hand while doing calculation by abacus.

**ABACUS COUNTING**

**Unit Column**

First column of our right side represents Unit Column / Unit digit (0 – 9)

Each bead of lower deck of our right column represents 1. The upper bead represents 5.

Move up 1 bead of unit column and touch the answer line with thumb finger, this is 1.

Then move up 2 beads of unit column and touch the answer line with thumb finger, this is 2.

Move up 3 beads of unit column and touch the answer line with thumb finger, this is 3.

Then move up 4 beads of unit column and touch the answer line with thumb finger, this is 4.

Now put down all the 4 beads of unit column with index finger and put down the red beads of upper deck to count 5.

In this way, if you add 1 beads with 5 it is 6, if you add 2 beads with 5 it is 7, if you add 3 beads with 5 it is 8, and if you add 4 beads with your 5 finger it will be 9.

In this way if all the beads of unit column touch the answer line this will be 9.

**Tens Column**

In Abacus the second right column will be tens column. Tens column’s each bead of lower deck will represent 10, and Upper bead of Tens Column will be 50.

Move up 1 bead of tens column and touch the answer line with thumb finger, this is 10.

Then move up 2 beads of tens column and touch the answer line with thumb finger, this is 20.

Move up 3 beads of tens column and touch the answer line with thumb finger, this is 30.

Then move up 4 beads of tens column and touch the answer line with thumb finger, this is 40.

Now put down all the 4 beads of tens column with index finger and put down the red beads of upper deck to count 50.

In this way, if you add 1 beads with 5o it is 60, if you add 2 beads with 50 it is 70, if you add 3 beads with 50 it is 80, and if you add 4 beads with your 50 finger it will be 90.

In this way if all the beads of tens column touch the answer line this will be 90.

If all the beads of tens column touch the answer line this will be 90 and all the beads of unit column will be 9. Altogether this will be 99.

**HOW TO DO ADDITION & SUBTRACTION IN ABACUS**

**Example 3 + 1 – 1**

Step 1 To add 3, move up three beads of unit column

Step 2 To add 1, move up 1 bead of unit column

Step 3 To subtract 1, move down 1 bead from lower deck.

Answer is 3.

CLASS WORK 1A

Now you are ready to do sums from your book.

1.3 try to finish this portion within 15 min. Page-3

1.4 try to finish this portion within 15 min. Page 3.

ORAL CALCULATION

Parent will tell the sums from abacus part and student need to do and write the answers maintaining numbering sequences. Listening to sums called out and doing the same to give answers not only enhances the listing skill but also the hearing sense establish better memory skills. Ability to do fast and accurate mental arithmetic calculation. Students will write answers one by one in Exercises 3 and 4.

HOME WORK 1 B.1

The home work will be 1B.1 page 2.

Lesson Content

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