Modeling and Understanding Percents
Pages 425-428 in Textbook
Objectives
• I can use models to represent percents.
• I can write percents as decimals and fraction.
Vocabulary
•
•
•
•
Percent:
Is a ratio that compares a number to 100.
The symbol for percent is:
%
Modeling Activity
• On your graph paper make a border to form a
10 x 10 grid. It should contain 100 squares
• Each of the small squares represents how
much?
• 1/100 or 1%
• To model 25%, how many squares should I
shade in?
• 25. Go ahead and shade them in.
Continued
• The shaded portion represents 25%, the
decimal 0.25, and the fraction 25/100= ¼
• Everyone model 35%.
• Then write it as a decimal and a fraction.
• 0.35, 35/100 = 7/20
• Try another
• 80%
Draw Conclusion
Reasoning
•
•
•
•
•
•
•
•
How would I model 100%
Shade in 100 squares
How would I model 150%?
Shade in 150 Squares
How would I model 200%?
Shade in 200 squares
How would I model .5%
Shade in half of a square
Understanding Percents
• A percent is what?
• A ratio that compares a number to 100.
• Percents means
– Per hundred
– Out of 100
– You can remember that percent means per
hundred by thinking of how many cents in a dollar.
Writing ratios in different forms.
A bag full of 100 marbles, has 43 blue, 7 red and
50 green.
You can write the ratio of blue marble to the
whole in three ways:
Percent: 43%
Decimal: 0.43
Fraction: 43/100
Write the ratio of red marbles in the three ways?
7%, 0.07, 7/100
Writing a percent as a decimal!
• Divide the value by 100:
• 57% = 57
100 = 0.57
• Or you can move the decimal two spots to the
left.
• Try a couple:
• 15%, 6%, 32.5%
Write a percent as a fraction!
• Rewrite the percent using a denominator of
100, Simplify if possible.
• 45%
• 45/100 = 9/20
• You try:
• 20%, 56%
We will continue with Modeling and Understanding
Percents.
Monday/Tuesday
We will be covering percents, decimals, and
fractions.
Wednesday/Thursday
We will be covering the percent of a number.