Math 7 · Unit 2, Lesson 4
Sales and Markups
Discounts, sales, markups, and markdowns.
I say it the way your test says it.
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.
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 |
|---|---|---|
| Discount | The amount taken off. | Original price times the discount rate. |
| Markdown | Another word for a discount. | Same move: take the percent off. |
| Sale price | What you pay after the discount. | Multiply by 1 minus the rate: 0.70 for 30 percent off. |
| Markup | The amount a store adds to what it paid. | Multiply by 1 plus the rate: 1.45 for 45 percent. |
| Original price | The price before any change. | When it is missing, ask what percent of it the sale price is. |
| Percent of what | The whole the percent is taken from. | Ask it before every multiplication. |
The big idea
A proportional relationship always multiplies by the same number, the unit rate.
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 changes in both directions. A discount takes a percent off, so you pay what is left: 30 percent off means times 0.70. A markup adds a percent on, like tax: 45 percent up means times 1.45. Times a number smaller than 1 makes it smaller, bigger than 1 makes it bigger. When the original price is missing, ask percent of what: the sale price is the percent that is left, so build up from there.
Exit ticket
On paper or an index card. Use the math word and the plain-English word.
- Sneakers cost $80 and are 25 percent off. What is the sale price?
- What one number do you multiply by for 30 percent off? For a 45 percent markup?
- A shirt is 40 percent off and costs $12 on sale. 40 percent of what?
Check your exit ticket
- $60.
- 0.70 and 1.45.
- Of the original price, $20, not of $12.
Printables
A one-page study guide with Elle and Finn, the two big-idea sentences, the multipliers for taking off and adding on, and the percent of what warning. Plus a worksheet with an answer key and a lesson plan that walks a parent or tutor through the three tiles.
Where this goes next
NC Grade 7 standards in this lesson: NC.7.RP.3.