# 1TH/vwo §6.1 From description to formula

Today we do:
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Slide 1: Slide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

This lesson contains 28 slides, with interactive quizzes and text slides.

Lesson duration is: 50 min

## Items in this lesson

Today we do:

#### Slide 1 -Slide

What is the learning goal today?

#### Slide 2 -Slide

First....
an amazing nature event !

#### Slide 5 -Slide

a. We read this text together.
b. Answer the question below in the next slide.
This is not an easy question.
So: concentrate!
timer
1:00

#### Slide 6 -Slide

Roughly how far away is the thunderstorm?
A
2 km
B
2 + 2/3 km
C
2.5 km
D
3 km

#### Slide 7 -Quiz

Solution:
It takes the thunder 3 seconds to travel 1 km.
So if you hear the thunder after 8 seconds, then it is
8 : 3 =                 km away. Or 2.7 km, rounded off.
However, because the question said 'roughly' (ongeveer) also
2.5 km is a good answer.
2+32

#### Slide 8 -Slide

Question:
In which line a MISTAKE is made in this text? ANS

they are all correct. It's about
meaning of events.
timer
1:00

#### Slide 9 -Slide

The mistake is in the ..... line.
A
1st
B
3rd
C
5th
D
7th

#### Slide 10 -Quiz

The MISTAKE is:
At first they say that the lightning
comes first and the thunder follows.
However then it's the other way round:
The thunder is followed by the
lightning!? Funny.

#### Slide 11 -Slide

In the 13th edition of the book this mistake is corrected,
as you can see below:

#### Slide 13 -Slide

A RULE in WORDS about thunder and lightning is:
If you divide the time in seconds the thunder takes to reach you by 3, you get the distance in km.

#### Slide 14 -Slide

This Rule in Words is changed into a Formula now:
We alredy have a RULE IN WORDS:
If you divide the time in seconds the thunder takes to reach you by 3, you get the distance in km.
Now we make a FORMULA:
time in seconds : 3 = distance in km

#### Slide 15 -Slide

timer
0:20
What does a Formula have, but a Rule in Words does not?

#### Slide 16 -Mind map

Solution:
A Formula has arithmetic symbols like:
+           -              x      :      and      =
What is described (=beschreven)  in a Rule in Words, is made into a Calculation in a Formula.

#### Slide 17 -Slide

Let's make a Formula now!
In the next exercise you get some information.
A) to make a Formula and then
B) to make a Calculation with it.
By the way: a Formula should be applicable (toepasbaar) for any number that you like to fill in.
For every number another outcome will follow.
A Formula does not have one fixed outcome!

#### Slide 18 -Slide

Weight of a box =  .............................     (the number of balls plays a part here!)
Note: You can also END your Formula by it, so like this:
..................................... =  Weight of a box.
timer
1:00

Formula .... ?

#### Slide 20 -Mind map

The correct Formula is:

number of balls x 60 + 250 = weight,  or
250 + number of balls x 60 = weight,  or
weight = number of balls x 60 + 250
So you see that there are more ways to write it down!

#### Slide 21 -Slide

The MAKING of a Formula ...
is more difficult than making CALCULATIONS with that
Formula.
You will notice this in the next slides.

#### Slide 23 -Slide

In the next slide, the Formula is repeated.
ANS

#### Slide 24 -Slide

Calculate the weight of a box containing 6 balls.
The Formula is:
number of balls x 60 + 250 = weight
timer
0:30
A
600
B
590
C
580
D
610

Solution:

#### Slide 26 -Slide

Summarising:
Sometimes you have a Description or a Formula in Words (that's the same).
You can change this into a Formula.
In a Formula you can fill in a given number, to get an outcome.
Like we just did.

#### Slide 27 -Slide

Homework time
Time to do §6.1 now.
You may skip exercises 1 and 2, as you already did a lot.
Don't forget to
+ check with the Solutionsbook    +    take pics and
+ send it in in GC.