Introduction to Number Line

Activity - Understanding integers, properties through number line

Source: IT for Change

Objectives

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

Estimated Time

60 minutes

Materials/ Resources needed

Paper, pencils/ sketch pens

Prerequisites/Instructions, if any

Students know basic number facts: Numbers are continuous, counting, quantities for ex: difference between 2 books,2 kgs of apples or 2 litres of milk,2 mts, etc

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

Process (How to do the activity)

Step 1

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.
2. Now ask boy and girl to come one after other to keep the number which they have written .
3. Suppose the first boy comes and keeps +5 then call other girl ask her to keep her number .
4. She can keep it anywhere she wants (imagine she has -7 on her sheet)
5. But the real fun starts when the third one(boy) will come(imagine he has +10 on his sheet)
6. 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

1. If the numbers are kept as above where +10 should be placed?why?
2. 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
3. +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

1. Is there any number missed in between?
2. 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 .
3. 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.

1. 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?)
2. 4+(-3)=+1 - The value of 4 decreased to +1when it is added to -3 (-3 decreases the value of 4 by how much?)
3. -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. -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)

1. What is the behaviour of -7 and -4

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

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

Evaluation (Questions for assessment of the child)

1. 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?

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