1TTO §8.4 Adding and subtracting fractions

§8.4 Adding and subtracting fractions.

Fractions??!

Forgotten all about them?

Next slide shows you some of those little fellas!

Just lean back and let yourself be informed.

1 / 24

Slide 1: Slide

WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

This lesson contains 24 slides, with interactive quizzes and text slides.

Lesson duration is: 30 min

Items in this lesson

§8.4 Adding and subtracting fractions.

Fractions??!

Forgotten all about them?

Next slide shows you some of those little fellas!

Just lean back and let yourself be informed.

Slide 1 - Slide

Slide 2 - Slide

A fraction has a ...... and a ....... see below!

The number above is called: the numerator ( = teller). It tells us: HOW MANY?

The number below is called: the denominator (= noemer). It tells us the

TOTAL of the numbers and it's also the NAME.

4 = numerator and

5 = denominator

\frac{​ 4 ​ ​}{​ 5 ​}

Slide 3 - Slide

Finally don't forget to SIMPLIFY the answer, if possible!

Slide 4 - Slide

Slide 5 - Slide

Slide 6 - Slide

Slide 7 - Slide

However ..... is it always just a piece of cake?

Slide 8 - Slide

When is it a bit more work to add or subtract fractions?
What kinda fractions are at stake then?

Slide 9 - Mind map

With 'common' denominators 'equal' ones are meant!

Slide 10 - Slide

Slide 11 - Slide

Slide 12 - Slide

3/4 - 2/5 = ....

Slide 13 - Mind map

explanation:

the new denominator becomes 4 x 5 = 20 now!

- = - =

\frac{​ 3 ​ ​}{​ 4 ​}

\frac{​ 2 ​ ​}{​ 5 ​}

\frac{​ 1 5 ​ ​}{​ 2 0 ​}

\frac{​ 8 ​ ​}{​ 2 0 ​}

\frac{​ 7 ​ ​}{​ 2 0 ​}

Slide 14 - Slide

Slide 15 - Slide

But .........

How to add or subtract fractions like:

3 and 6 ?

Next slide explains more.

\frac{​ 5 ​ ​}{​ 6 ​}

\frac{​ 3 ​ ​}{​ 4 ​}

Slide 16 - Slide

Slide 17 - Slide

The following slide ...

Asks for your complete attention,

as it deals with tricky fraction facets!

Unequal denominators and more

trouble...

Slide 18 - Slide

Slide 19 - Slide

Just think hard about this one!

How to do it?! Think about common denominators, of course.

What is the final outcome?

Maybe you'll get the turn to share your answer!

Slide 20 - Slide

Slide 21 - Slide

5 2/3 + 7/11 =

Slide 22 - Mind map

Homework time

Slide 23 - Slide

Slide 24 - Slide