1 FRACTIONS, DECIMALS, AND PERCENTS Week 4. Helen Holt2 Session Outcomes: Be able to read, write,...
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Transcript of 1 FRACTIONS, DECIMALS, AND PERCENTS Week 4. Helen Holt2 Session Outcomes: Be able to read, write,...
1
FRACTIONS, DECIMALS, AND
PERCENTS
FRACTIONS, DECIMALS, AND
PERCENTS
Week 4
Helen Holt 2
Session Outcomes:• Be able to read, write, order and
compare common fractions.
• To identify equivalences between fractions, decimals and percent.
• To identify the relationship between fractions, decimals and percent.
• To explore misconceptions of fractions.
Helen Holt 3
What are fractions?• Fractions, decimals and percents are different
ways of representing an amount.
• I.e. We could say 50% of something, or ½ or 0.5. These are all the same quantity.
• Fractions are about sharing. You may like to think of them as ‘parts of a whole’.
Helen Holt 4
What are fractions?• A fraction describes part of
a whole when the whole is cut into equal parts.
• This pizza has been cut into three equal parts. We call these thirds. A third is written as:
• Think about two slices. Two slices is two thirds:
Helen Holt 5
Writing fractions?
• Look at the pictures below. How many parts are these shapes divided into? Represent these shapes as fractions.
Helen Holt 6
Converting between fractions, decimals and %:
A same value can be written in differentforms. For example:
½ 0.5 50%To convert a fraction into a decimal, divide the top of the fraction by the bottom of the fraction:
e.g. ½ = 1÷2 = 0.5
To convert a decimal into a percentage, multiply by 100:
e.g. 0.5 x 100 = 50%
Is the same as:
Is the same as:
Helen Holt 7
Converting between fractions, decimals and %:
Place the fraction, decimal and % into the correct blank spaces on the grid.
Fraction
Decimal
%
½ 0.5
¼ 25%
0.20
1/10 10%
0.75 75%
3/9
100%
Helen Holt 8
Fraction Decimal %
½ 0.5
¼ 25%
0.20
1/10 10%
0.75 75%
3/9
100%
Helen Holt 9
Why use fractions, decimals and %?
When might we use fractions:
• When telling the time (e.g. ¼ past).• In shop sales (e.g. a 1/3 off, ½ price).• When measuring (e.g. ½ a metre).
• When dividing (e.g. 1 pizza divided between 6 people).
• In recipes (e.g. half a dozen).
When might we use decimals:
• When working with money.• To show probability, or the likelihood
of something happening.• To show how many whole and part
numbers there are to a value (e.g. 3.25 means 3 whole numbers and one quarter of a whole number).
When might we use %:
• Shops use percentages in sales.• Banks use them for loan rates,
mortgages, savings accounts..• Weather forecasts use them to tell us the chances of rain. • To calculate VAT and income tax.
When working in business we may choose between fractions, decimals and %s to make a sale item look more appealing to customers. For example, 20% off may sound more appealing than 1/5 off a sale item, even though they are really the same amount!
Helen Holt10
Where can we find fractions?
Take a look at this article. Notice how fractions are used to explain and analyse the results of the survey.
Helen Holt 11
Fraction Decimal %
½ 0.5 50%
¼ 0.25 25%
1/5 0.20 20%
1/10 0.1 10%
3/4 0.75 75%
3/9 0.333 33.3%
1/1 1.00 100%
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WANT TO PLAY A COMPUTER GAME?
• http://www.math-play.com/Changing-Fractions-and-Decimals-to-Percents/changing-fractions-and-decimals-to-percents-millionaire.html
• http://www.mathplayground.com/Decention/Decention_IWB.html
Helen Holt