1. The Short End of the Stick
NS 1.7 Solve problems that include discounts, markups, commission, and profit and compute simple and compound interest.

2. Content Objective
Using a length model, we will make sense of and solve problems involving percents.

3. Language Objective
I will use a length strip to identify 10% increments, label the strip, and find the value of a particular percent of a whole.

4. Number Talk What is 50% of $40? 10% of $40? 10% of $80? 10% of $65?
So, how do we find 10% of any number?
Chart different student methods of solving.

5. Lesson Introduction
A video game is 50% off of the original price and you have a coupon for an additional 50% discount off of the sale price. Does this make the item free? Write your prediction. Then share your prediction with a partner.
$80

6. Regular Price
$90
This bike is on sale for 10% off the regular price. What is the amount of the discount? What is the sale price of the bike? 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Chart original, discount, and sale price. $9 $9 $9 $9 $9 $9 $9 $9 $9 $9 $0 $9
$18
$27
$36
$45
$54
$63
$72
$81
$90

7. This ipod is on sale for 10% off the regular price
This ipod is on sale for 10% off the regular price. What is the discount amount? What is the sale price of the ipod?
Regular Price
$200 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Chart original, discount, and sale price.
$20
$20
$20
$20
$20
$20
$20
$20
$20
$20 $0
$20
$40
$60
$80
$100
$120
$140
$160
$180
$200

8. This ipod has an additional mark down of 20% off the sale price
This ipod has an additional mark down of 20% off the sale price. What is the new discounted price of the ipod?
Sale Price
$180 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Chart original, discount, and sale price.
$18
$18
$18
$18
$18
$18
$18
$18
$18
$18 $0
$18
$36
$54
$72
$90
$108
$126
$144
$162
$180

9. Additional Practice
An item that costs $60 is discounted 30%. What is the discount amount?
What is the sale price when $80 is discounted by 20%?
What is the final price when an item costing $120 is marked down 60%?
A shirt costs $35 and is marked down 20%. What is the sale price of the shirt?
Extension: Ask students to see if they can solve additional practice problems in more than one way. Then allow students to share with the class by making posters or showing under doc. camera.
Challenge Problems:
You paid $5.00 for an item that was discounted 90%. What was the original cost of the item?
The original cost of an item was $30. You paid $24. What was the percent discount?

10. Lesson Conclusion
A video game is 50% off of the original price and you have a coupon for an additional 50% discount off of the sale price. Does this make the item free? Look at your original prediction. Use 2 length strips to determine if your prediction was correct and explain why.
$80

11. Day 2 Content Objective
Using a length model, we will make sense of and solve problems involving percents.

12. Language Objective
I will use a length strip to show my solution to problems involving percent discounts. I will be able to explain my solution to my partner.

13. Language Objective
I will use a length strip to show my solution to problems involving percent discounts. I will be able to explain my solution to my partner.

14. Number Talk What is 10% of $40? 15% of $40? 20% of $40? 25% of $40?
Ask students to try to solve in more than one way. Chart different student methods of solving.

15. This ipod has an additional mark down of 20% off the sale price
This ipod has an additional mark down of 20% off the sale price. What is the new discounted price of the ipod?
Sale Price
$180 0%
25%
50%
75%
100%
Chart original, discount, and sale price.
$18
$18
$18
$18
$18
$18
$18
$18
$18
$18 $0
$36
$90
$126
$180