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Ratios and Data 6-8 / Week 03 / Friday
5/6
Week 03 · Percents

Friday

Percents all around
// A rate per 100
⏱ about 20 min

Friday: Percents All Around

Rocket holds up the kitchen tablet. "Battery 40%. That is a percent. The whole is a full battery."

Raven points at the oven timer. "Zero. That is not a percent. It is just a clock."

"A quiz score, 18 out of 20," Rocket says. "That is 90%!"

"What do you notice about every real percent?" Raven asks. Rocket thinks. "There is always a whole hiding behind it."

Nova hovers between them. "Then here is the hard one. A download bar says 75% done after 15 minutes. How long in all?"

Rocket grabs the Numbers Notebook. "25% is 5 minutes. So 100% is 20 minutes." Raven nods. "The whole, found."

Percents in everyday life

A percent always has a whole behind it: a full battery, all the quiz questions, the whole download.

A battery at 40% has 40 of every 100 parts of its charge left. A score of 90% means 90 of every 100 points.

When you see a percent, ask two questions. What is the whole? What is the part?

Two percents with different wholes cannot be compared directly. Half of a small battery is less charge than half of a big one.

  • Battery level: the whole is a full charge.
  • A quiz score: the whole is every question.
  • A progress bar: the whole is the finished job.
  • The sign-up sheet: the whole is every kid who signed up.
REVIEW: PERCENTS FROM PARTS
  • Read the question.
  • Tap your answer.
A quiz has 20 questions and Raven gets 18 right. What percent is that?
Rocket reads 9 of the 12 chapters in a book. What percent has he read?
A seedling tray has 50 cups and 30 have sprouted. What percent sprouted?
A progress bar shows 3 of 4 files copied. What percent is done?
REVIEW: PARTS AND WHOLES
  • Read the question.
  • Tap your answer.
A battery at 40% started with 80 units of charge. How many units are left?
A download is 75% done after 15 minutes. How many minutes will the whole download take?
A score of 90% on a 20-question quiz means how many right answers?
9 sprouted cups are 45% of a tray. How many cups does the tray have?
REVIEW: THREE WAYS TO SAY IT
  • Read the question.
  • Tap your answer.
Which percent equals 1/10?
Which percent equals 0.6?
Which percent equals 4/5?
Which percent equals 0.05?
Number sentenceTrue or false?
18/20 = 90/100?
40/100 × 80 = 32?
1/10 = 0.01?
3/5 = 0.6?
15 ÷ 75 × 100 = 20?
WHY THIS EXERCISEThe week's three moves: part to percent, percent of a number, and whole from a part.

Look ahead: dividing fractions

Next week the crew shares supplies. How many 1/4-cup scoops fill 3 cups? That is dividing by a fraction.

You will use strips and number lines, the same pictures that showed ratios and percents.

Draw one everyday percent you saw today, with its whole and its part labeled.

A full week of percents. Tomorrow is Data Day: the family hunts percents at home.

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