1TH/vwo §8.2 Adding negative numbers

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 1

§8.2 Adding negative numbers

12   t/m   16

LEARNING GOAL:

How to add NEGATIVE NUMBERS together

We're gonna do some adding ...

with Positive and especially Negative Numbers!

As usual...

this LessonUp marches through the most

important aspects of the whole paragraph,

making it much easier to deal with it yourself, afterwards!

We're gonna do several exercises together, so: less homework.

A special role is reserved today for a peculiar, be it somewhat creepy, person: A Witch!

The witch is toying with her

HOT BLOCKS and COLD BLOCKS!

How does this work?!           Like this:

The witch has a cauldron. (=kettle)

You better not taste one of her brews (brouwsels)...

+ she puts in HOT BLOCKS and also

+ COLD BLOCKS 

+ to control the temperature

+ every Blocks represents one degree!

The temperature is 0 degrees.
The witch adds 5 cold blocks. (1 block = 1 degree)
What's the new temperature?

1. 5 degrees
2. +5 degrees
3. -5 degrees
4. 0 degrees

There are 13 cold blocks and 7 hot blocks in the cauldron.
What is the temperature?

1. -6 degrees
2. 6 degrees
3. 20 degrees
4. -20 degrees

Explanation:

13 cold blocks correspond to -13 degrees

7 hot blocks correspond to +7 degrees,

so the calculation is:

-13 + 7 = -6

In the next slide...

+ many changes in temperature come up!

+ your teacher will tackle the first line

+ then all think about the next line

+ one of you will get the turn!

+ and so on with the 3rd line, etcetera

That may all be true, but ...

it's high time for a Joke!

What's this?!

Do I see a '+' and a '-' in a row?

Yes, you do. The '+' is for 'adding' and the '-' is for the negative number: '-7'.

Next slide ...

+ offers us a huge table again

+ your teacher will take care of the first line again

+ then some of you get the turn to tackle the next lines

+ maybe youthink it's all still very simple(?)

+ beware: next lesson the Witch will also TAKE OUT Hot en Cold Blocks;

+ so it's important to understand the ADDING of Blocks first! 

Not really surprising, this, but good to realise!

All think about the following TASK:

What ADDITION is described above?

Key it in, in the next slide!

The ADDITION is:

Solution:

-35 + 40 = 5

-6 + .... = -9

A task for you:

-6 + .... =  -9

What to fill in here?

-6 + ...... = -9

The number to be filled in is:

-3 !

At last ... a JOKE!

Finally:

        An example of this follows!

What all this?!?

Negative numbers and Fractions too!

This is too difficult for me, Mr. Hauwert!

Okay, next slide shows you a fine way to tackle such ones!

VWO only

Now think about this one for a while!

                               Key in your answer in the next slide.

13​5​​2​​

+ ... = -2.5

VWO only

Using the number line, you see that you have to

add up the length from 13        till 0,

and the length from 0 to -2.5 !

That is:   13       +   2         =     15 

However we go from positief to negative,

so we subtract. The answer is:  -15.9

​5​​2​​

​5​​2​​

​10​​5​​

​10​​9​​

Homework time

We skip a lot of tasks.

Make:       12, 13, 14, 15, 16. plus

                    C3 + C4  A little more about the Challenge tasks follow                       later.

and send them in in GC.

TIP 1:

in order to make the Graph, first make a TABLE!

Taking the three numbers. 0, 4 and 8 for 'number of buttons' is enough.

(The Solutionsbook takes many more...)

Feel free to make this task 

in your Flexbook.

However use a PENCIL, for good reasons.

If one number is placed wrongly with a pen,

it will get an ugly picture.