Math 7 · Unit 2, Lesson 2

Part, Whole, and Percent

Finding the missing piece.

About 25 minutesWhich piece is missing?

ElleMath-speak

I say it the way your test says it.

FinnPlain English

And I say it the way you would say it to a friend. Same idea, two ways.

Write it down. Do every step on paper, one line per step. Percent problems go wrong in your head, not on the page. If you changed something, it should be on the paper.

Go in order. Each tile has a short explanation, then a "Let me try a few" button.

1The Three PiecesWhole, part, and percentStart here 2Find the PartWhat is 40 percent of 35? 3Find the Percent or the WholeWorking backward on the bar

When you have finished

At the end of each tile you will find a review form to give us feedback.

NC standards: NC.7.RP.3.

Words we use

Word	Plain English	What you do
Whole	All of it, 100 percent.	Find the thing the percent is taken of.
Part	Some of it.	Find the share that is less (or more) than the whole.
Percent of	Multiply the whole by the percent as a decimal.	Read of as times: 40% of 35 is 35 times 0.40.
Proportion	Two equal ratios, from Unit 1.	Part over whole equals percent over 100, when it comes from reasoning.

The big idea

ElleMath-speak

A proportional relationship always multiplies by the same number, the unit rate.

FinnPlain English

Percent means out of 100. A percent is a unit rate for 100 instead of for 1: 30 percent means 30 for every 100.

This lesson added the three pieces. Every percent problem has a whole (all of it), a part (some of it), and a percent (the share out of 100), and one of them is missing. Find the part by building from 10 percent or by multiplying the whole by the percent as a decimal. Find the percent by writing part over whole. Find the whole by finding 10 percent and building up to 100. The percent bar shows all three at once.

Exit ticket

On paper or an index card. Use the math word and the plain-English word.

What is 15 percent of 60?
18 of 24 free throws went in. What percent is that?
$45 is 30 percent of the price of a bike. What is the price?

Check your exit ticket

9.
75 percent.
$150.

Printables

A one-page study guide with Elle and Finn, the two big-idea sentences, the three pieces, and the three missing-piece types on the percent bar. Plus a worksheet with an answer key and a lesson plan that walks a parent or tutor through the three tiles.

Study guide (PDF) Worksheet and answer key (PDF) Lesson plan (PDF)

Where this goes next

Previous lesson: What Percent MeansPercent means out of 100. Next lesson: Tax, Tips, and FeesTax, tips, commission, and fees. Back to the Math 7 mapEvery 7th grade lesson, in course order.

NC Grade 7 standards in this lesson: NC.7.RP.3.