# 1TTO §9.2 + §9.3 once more.

Some more practice with §9.2 and §9.3
Nothing new, this time.
This makes sense, as doing adding and subtracting with
positive and negative numbers is quite tricky!
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Slide 1: Slide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

This lesson contains 10 slides, with text slides.

Lesson duration is: 45 min

## Items in this lesson

Some more practice with §9.2 and §9.3
Nothing new, this time.
This makes sense, as doing adding and subtracting with
positive and negative numbers is quite tricky!

#### Slide 1 -Slide

This lesson ...
+ you'll get a lotta time to work for yourself
+ first however: a short look back at §9.2 and §9.3

#### Slide 2 -Slide

6 + 7 = 13
The simplest type of exercise.
A positive number, 7, is added to a number. This makes the result greater than the start:     13 is greater than 6.

#### Slide 3 -Slide

video Math Antics

#### Slide 4 -Slide

7 + -4 = 3
A NEGATIVE number is added to a number.
Now the result is less:  3 is less than 7.

#### Slide 5 -Slide

Subtracting 1:
8 - 5 = 3
A Positive number is subtracted from a number.
the result is less:   3 is less than 8.
Beware of the last type, next slide!

#### Slide 6 -Slide

Subtracting 2:
6 - -5 = ....
This is the most difficult type!
If a negative number is subtracted, it has the same effect as adding the positive number: 6 - -5 = 6 + 5 = 11

#### Slide 7 -Slide

Once more the whitch's cauldron:
6 - -5 = ....
Suppose the start temperature in the cauldron
is 6 degrees. Now she takes out 6 Cold Blocks.
then it gets warmer in the cauldron!
So taking out cold blocks does the same as putting in hot blocks.
So: 6 - -5 = 6 + 5 = 11

#### Slide 8 -Slide

+ §9.2 and §9.3, that we just discussed
+ fractions(!); they keep popping up now and then;
that's why it makes sense doing some basic fraction tasks now.

#### Slide 9 -Slide

homework time
Now make and check: Make of 9.3: ex. 21, 23, S23 (p. 59) and S6 (page 72).