1TH/vwo §8.4 Multiplying and division

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Slide 1: Slide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

This lesson contains 31 slides, with interactive quizzes and text slides.

time-iconLesson duration is: 30 min

Items in this lesson

Slide 1 - Slide

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 - Slide

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 - Slide


Think about this and answer in the next slide.

Slide 4 - Slide

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 - Quiz

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 - Slide

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 - Quiz

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 - Slide

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

Slide 9 - Slide

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 - Quiz

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 - Slide

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

Slide 12 - Slide

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

Slide 13 - Mind map

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 - Slide

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

Slide 15 - Slide

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 - Slide

Slide 17 - Slide

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

Slide 18 - Slide

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 - Slide

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 - Slide

The reverse of multiplying is ....
dividing!

Slide 21 - Slide

Key in your answer in the next slide!

Slide 22 - Slide

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 - Quiz

                       Solution:
                       -3 x -8 = 24

Slide 24 - Slide


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 - Slide

Slide 26 - Slide

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

Slide 27 - Slide

-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 - Quiz

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 - Slide

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 - Slide

That's all, folks!

Slide 31 - Slide