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 ConclusionReasoning

• 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: 0.43Fraction: 43/100Write 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/ThursdayWe will be covering the percent of a number.