This lesson contains 17 slides, with interactive quizzes and text slides.

Items in this lesson

Slide 1 - Slide

-8 ... -7

A

<

B

=

C

>

Slide 2 - Quiz

If you walk to the right you add

If you walk to the left you subtract (-)

If you add or subtract a postive number you walk forwards

If you add or subtract a negative number you walk backwards

Look at the picture on the right.

If you add a number you turn your nose to the right

If you subtract a number you turn your nose to the left

If you add or subtract a positive number you walk forwards

If you add or subtract a negative number you walk backwards

Slide 3 - Slide

If you walk to the right you add

If you walk to the left you subtract (-)

If you add or subtract a postive number you walk forwards

If you add or subtract a negative number you walk backwards

Adding (walk to the right) a positive number (walking forwards)

8 + 6 = 14

Slide 4 - Slide

If you walk to the right you add

If you walk to the left you subtract (-)

If you add or subtract a postive number you walk forwards

If you add or subtract a negative number you walk backwards

Subtracting (nose to the left) a negative number (walk backwards).

If you stand at position 8 on the number line, nose to the left and you walk backwards 6 steps you end up at 14.

8 - -6 = 14

Slide 5 - Slide

We can see that both examples have the same answer:

8 + 6 = 14 and also

8 - -6 = 14

Conclusion: subtracting a negativen number is the same as adding a positive number !!!

Slide 6 - Slide

By the way....

The brackets around -6 in the picture are not necessary (nodig) but are just to clarify that the negative minus belongs to the 6. In class we will not write these brackets

Slide 7 - Slide

-6 + - 10 = ?

A

-4

B

4

C

6

D

-16

Slide 8 - Quiz

Now let's start practising...make the next exercises and fill in your answer. Important, if your answer is a negative number do not write a space in between the minus sign and the number.

Now let's start practising with the next exercises. There is an automatic check if your answer is correct. This will only work if you do not write a space between a negative sign and the number. For example, if your answer is minus 5 just typ -5 and not: - 5 . Okay? :D

Slide 9 - Slide

10 - 12

Slide 10 - Open question

30 + -12

Slide 11 - Open question

-3 - 5 =

Slide 12 - Open question

4 - -11=

Slide 13 - Open question

-10 - -4 =

Slide 14 - Open question

-7 - -7 =

Slide 15 - Open question

8 + -9=

Slide 16 - Open question

Let's do some exercises

What? Do the test yourself unit 1.5

How? On your own (in silence) Time? 6 minutes Help? Raise your hand.