# Building the number line

# Activity - Understanding numbers, properties through number line

## Objectives

- Understanding what is a number line
- Understanding properties(behaviour) of positive and negative numbers through number line
- Understanding number sentences /operations of numbers on the basis properties of numbers.
- Compare numbers/ordering numbers

## Estimated Time

60 minutes

## Materials/ Resources needed

Paper, pencils/ sketch pens

## Prerequisites/Instructions, if any

Students know about numbers,Numbers are continuous, counting, quantities for ex: difference between 2 books,2 kgs of apples or 2 litres of milk,2 mts .....

Please emphasise that positive numbers increase the quantities and negative numbers decreases the quantity(amount)

## Multimedia resources

## Website interactives/ links/ simulations/ Geogebra Applets

## Process (How to do the activity)

### Step 1

- Ask boys to write positive number and girls to write negative numbers on a sheet of paper. Each one should write one number. Instruct them to arrange the numbers in order on the floor.
- Now ask boy and girl to come one after other to keep the number which they have written .
- Suppose the first boy comes and keeps +5 then call other girl ask her to keep her number .
- She can keep it anywhere she wants (imagine she has -7 on her sheet)
- But the real fun starts when the third one(boy) will come(imagine he has +10 on his sheet)
- You have to help him to keep the number in a proper order as he will have a positive number you should guide him where he should keep it and why?

- +5
- -7

- If the numbers are kept as above where +10 should be placed?why?
- For this we need to explain +5 has property of increasing the quantity by 5 whereas -7 has a property of decreasing the quantity by -7,(+5 is more than -7) so where should be place for +10

. - +10 has a nature of increasing the quantity more than what +5 does .so keep it above +5.

(+10 is more than +5)

- +10
- +5
- -7

If the next girl comes with -4 ,where she should keep it?

Continued pattern will be

- +10
- +5
- -4
- -7

Place all the numbers what they have written on the sheet.

### Step:2

Ask them

- Is there any number missed in between?
- If the answer is yes ask them again to write the missed numbers and repeat the activity by placing those numbers in a right place, which completes the number line. Now explain number line is a model for representing numbers .
- Now the number pattern will look like this after filling the gaps

- -9
- -8
- -7
- -6
- -5
- -4
- -3
- -2
- -1
- 0
- +1
- +2
- 3
- 4
- 5
- 6
- 7
- 8
- 9 (You can also ask which is the last number?) The number arrangement need not be horizontal

### Step:3

Now write some number sentences as below .Help them to interpret the sentences.

- 4+(+3)=+7 - The value of 4 increased to +7 when it is added to +3 (+3 increases the value of 4 by how much?)
- 4+(-3)=+1 - The value of 4 decreased to +1when it is added to -3 (-3 decreases the value of 4 by how much?)
- -4+(+3)=-1 - The value of -4 increased to -1 when it is added to +3 (+3 increases the value of -4 by how much?)
- -4+(-3)=-7 - The value of -4 decreased to -7 when it is added to -3 (-3 decreases the value of -4 by how much?)

## Developmental Questions (What discussion questions)

- What is the behaviour of -7 and -4

(-7 decrease the quantity by 7 where as -4 decrease any quantity just by 4)

- Try to extract from them that -4 is more than -7.

## Evaluation (Questions for assessment of the child)

- Students can be asked to cite examples where positive and negative numbers are used in daily life.

Ex: Money (profit/loss), Elevation

2. What do positive and negative numbers represent while dealing with money?

3. What do positive and negative numbers represent while dealing with elevation /depth?

## Worksheets

## Question Corner

## Activity Keywords

**To link back to the concept page**
Numbers