1TH/vwo §8.4 Multiplying and division

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Slide 1: Tekstslide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

In deze les zitten 31 slides, met interactieve quizzen en tekstslides.

time-iconLesduur is: 30 min

Onderdelen in deze les

Slide 1 - Tekstslide

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 2 - Tekstslide

strange witch - funny brews ...
Remember the witch? From all the strange brews.
Once upon a day she wants to work quicker
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 3 - Tekstslide


Think about this and answer in the next slide.

Slide 4 - Tekstslide

Adding a bucket of 6 cold blocks
4 times makes the temperature in the cauldron ...
timer
0:20
A
rise
B
fall
C
stay the same

Slide 5 - Quizvraag

Answer:
Adding COLD BLOCKS make 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 6 - Tekstslide

Adding 6 cold blocks 4 times make the temperature fall by ... degrees.
timer
0:30
A
24
B
-24
C
6
D
-6

Slide 7 - 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 8 - Tekstslide

Think about it carefully.
Answer in the next slide again.

Slide 9 - Tekstslide

What happens to the temperature if 3 Cold Blocks are REMOVED 5 times?
timer
0:25
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 10 - Quizvraag

Solution:
This is a bit tricky!
Removing cold blocks makes it LESS COLD  in the kettle.
So it gets 5 x 3 = 15 degrees WARMER!

Slide 11 - Tekstslide

Task: 
answer c, below, in the next slide.

Slide 12 - Tekstslide

timer
0:30
removing a bucket of 3 cold blocks 5 times
gives this calculation:

Slide 13 - Woordweb

Solution Task c:
- 5 x -3 = 15                           So: minus times minus is positive.                                              or:                                                    -            x            -        =      +
' -3 '   means 3 COLD Blocks and
'-5'      means 5 buckets are REMOVED from the cauldron.




Slide 14 - Tekstslide

Question : What mistake was made in the 2nd line? ('removed 6 times .......')

Slide 15 - Tekstslide

The mistake in the second line is:
-6 x 8 = ....    this wrong, as it read that there were 8 COLD blocks!
-6 x -8 = 48     is what it should've been!
Now a little joke.

Slide 16 - Tekstslide

Slide 17 - Tekstslide

The funny part is this:
To have been around the block means also:
to have a lot of experience with something!

Slide 18 - Tekstslide

Let's discuss this table.
First ALL THINK ABOUT the 1st line. Then ONE GETS THE TURN to explain it.
Then we do the same with the 2nd line, etcetera.

Slide 19 - 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 20 - Tekstslide

The reverse of multiplying is ....
dividing!

Slide 21 - Tekstslide

Key in your answer in the next slide!

Slide 22 - Tekstslide

24 : -8 = -3, because ....
(make the multiplication!)
timer
0:20
A
3 x -8 = -24
B
-3 x 8 = -24
C
-3 x -8 = 24
D
3 x 8 = 24

Slide 23 - Quizvraag

                       Solution:
                       -3 x -8 = 24

Slide 24 - 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 25 - Tekstslide

Slide 26 - Tekstslide

Think about it.
Key in your answer in the next slide!

Slide 27 - Tekstslide

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

The Numbers to be filled in are:
timer
0:45
A
-2, -2, 9, 18
B
-2, -2, -9, -18
C
2, -2, -9, 18
D
2, 2, -9, -18

Slide 28 - Quizvraag

SOLUTION:
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 29 - Tekstslide

Homework:
          
All do:  30  t/m  35
HV1X: also do S 30 and S32, p.63
G1X:   also do C7 +  C8,  p.63


Slide 30 - Tekstslide

That's all, folks!

Slide 31 - Tekstslide