# 1TTO §8.4 Multiplying and division PTI June24

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 / 23
Slide 1: Tekstslide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

In deze les zitten 23 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 efficiently
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!

#### Slide 5 -Tekstslide

Adding 6 cold blocks 4 times makes 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?
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 10 -Tekstslide

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 11 -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 12 -Tekstslide

The reverse of multiplying is ....
dividing!

#### Slide 14 -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 15 -Quizvraag

Solution:
-3 x -8 = 24

#### Slide 16 -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 19 -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 20 -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  !

Homework:

Evaluation