Lesson 1: Understand Percent6.AT.4

I can…

I can explain a percent as a rate per 100, model it on a decimal grid or tape diagram, and interpret percents greater than 100%.

Key words

• Understand Percent — A percent tells how many out of 100.
• Percent — A number out of 100, shown with the % sign.
• Per hundred — For every group of 100. That is what percent means.
• Decimal grid — A grid of 100 squares. Each square is one percent.
• Part-to-whole — Compares one piece with the whole group.
• Greater than 100% — More than the whole thing. It is over 100%.
• Equivalent ratio — Ratios that compare in the same way.
• Tape diagram — A bar cut into equal parts to show amounts.

Steps

1. Students voted on a mascot, and 4 out of every 10 voters chose the tiger. I want to know how many that is out of 100.
2. "4 out of every 10" is a ratio, so I write an equivalent ratio with 100 as the second term. Multiplying both terms by 10 gives 40 out of 100.
3. On a decimal grid of 100 squares, I shade 40 squares — one square for each percent.
4. 40 out of 100 is written 40%. So 40% of the students voted for the tiger.

Try it

Seven out of every ten socks in the laundry basket are white. What percent of the socks are white, and how do you know?

Check your answer

70%, because 7 out of 10 equals 70 out of 100

Percent means per hundred. Multiplying both terms of 7 : 10 by 10 gives the equivalent ratio 70 : 100, which is 70%.

Sentence starter

I know ___ because ___.

Goal: I can explain what a percent means using the words per hundred, part, whole, and equivalent ratio.