# 1TTO §9.4 Multiplying and division PTI

1GHJK
It is good to realise that x  and  :  are each others reverse!
For example:
48 : 8 = 6,  because 6 x 8 = 48 !
In this LessonUp you will get
+ new Information and
+ also quite a few short Tasks,
to Practise this new Information.
1 / 25
Slide 1: Tekstslide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

In deze les zitten 25 slides, met interactieve quizzen en tekstslides.

Lesduur is: 30 min

## Onderdelen in deze les

1GHJK
It is good to realise that x  and  :  are each others reverse!
For example:
48 : 8 = 6,  because 6 x 8 = 48 !
In this LessonUp you will get
+ new Information and
+ also quite a few short Tasks,
to Practise this new Information.

#### Slide 1 -Tekstslide

Remember the woman with the soup and drinks.
Once upon a day she wants to work more handy
with her cold and hot blocks.
She wants to put in or take out MORE temperature blocks
IN ONE GO! For this she uses a BUCKET.
This is what this § is about.

#### Slide 2 -Tekstslide

When you add or remove a larger number of blocks in one go:

You add a bucket of 6 cold blocks four times.
Does the temperature rise or fall?
By how many degrees?

#### Slide 3 -Tekstslide

Adding a buckets of 6 cold blocks
4 times makes the temperature in the cauldron ...
A
rise
B
fall
C
stay the same

#### Slide 4 -Quizvraag

Adding COLD BLOCKS makes the temperature fall.
NEW QUESTION: By how many degrees does it fall?
Remember: she adds 6 cold blocks 4 times!
Answer in the next slide!

#### Slide 5 -Tekstslide

Adding 6 cold blocks 4 times make the temperature fall by ... degrees.
A
24
B
-24
C
6
D
-6

#### Slide 6 -Quizvraag

SOLUTION:
The temperature gets lower, of course!
However, it falls by 24 degrees and not by -24 degrees.
In other words: is gets colder by 24 degrees.

#### Slide 7 -Tekstslide

What happens to the temperature if 3 Cold Blocks are REMOVED 5 times?
Think about it carefully.
Answer in the next slide again.

#### Slide 8 -Tekstslide

What happens to the temperature if 3 Cold Blocks are REMOVED 5 times?
A
it falls by 3 degrees
B
it rises by 3 degrees
C
it falls by 15 degrees
D
it rises by 15 degrees

#### Slide 9 -Quizvraag

removing 5 times 3 cold blocks:
Solution:
This is a bit tricky!
Removing cold blocks makes it LESS COLD  in the kettle.
out 5 times three cold blocks =
- 5  x  -3 => it gets 5 times less cold because you remove cold blocks
So it gets 5 x 3 = 15 degrees WARMER!

#### Slide 11 -Tekstslide

answer c, below, in the next slide.

#### Slide 12 -Tekstslide

removing a bucket of 3 cold blocks 5 times
gives this calculation:

#### Slide 13 -Woordweb

Question 1: What should be filled in in the 1st line?
Question 2: What mistake was made in the 2nd line? ('removed 6 times .......')

#### Slide 14 -Tekstslide

Above you see the Basic Rules for Multiplying with
Positive and Negative Numbers.
Realise that you can always relate all these Calculations
to:     Hot and Cold Blocks in a number of Buckets, that are added or removed from the kettle!

#### Slide 15 -Tekstslide

The reverse of multiplying is ....
dividing!

#### Slide 16 -Tekstslide

Key in your answer in the next slide!

#### Slide 17 -Tekstslide

24 : -8 = -3, because ....
(make the multiplication!)
A
3 x -8 = -24
B
-3 x 8 = -24
C
-3 x -8 = 24
D
3 x 8 = 24

#### Slide 18 -Quizvraag

Solution:
-3 x -8 = 24

#### Slide 19 -Tekstslide

In this way, we can make Basic Rules for all 4 types of
divisions (=delingen) with positive and negative numbers!
See next slide.

#### Slide 21 -Tekstslide

Key in your answer in the next slide!

#### Slide 22 -Tekstslide

-18 : -9 = ......
because ..... x ..... = .....

The Numbers to be filled in are:
A
-2, -2, 9, 18
B
-2, -2, -9, -18
C
2, -2, -9, 18
D
2, 2, -9, -18

#### Slide 23 -Quizvraag

We just learned that:
a negative number divided by a negative number is a positive number.
So            - 18 : -9 = 2, because 2 x -9 = -18  !

#### Slide 24 -Tekstslide

Homework:
Make  30   up to and including  34