1. Licensing information
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This material is licensed under the Creative Commons Attribution-Share Alike license: (
Author: Kevin Hall
Wording for the legal statement above is adapted from the legal statement for Trigonometry, published in 2009 by The CK-12 Foundation:

2. Teaching notes
For questions listed as “worked examples” on the 2.3 student handout, the teacher shows the solutions step-by-step, and students answer the reflection questions on the handout.
For questions listed as “practice” on the student handout, do NOT show the complete solution until students have had a chance to work through it on their own. You can show it gradually while they work, timing it so each step comes up after most students have done that step.
While they work, you can walk around the room praising their success and prompting them where necessary.
Print out the solutions before class, so you’re not trying to solve the problems when you’re supposed to be walking around checking their understanding.

3. EXAMPLE: If you earn $9 every 2 hours, how much will you earn in 18 hours?
Studying this example problem will help you solve the next question on your own.

4. 2). EXAMPLE: If you earn $9 every 2 hours, how much will you earn in 17 hours?
$ 4.50
a). Can you explain this part?
$ 4.50
$ 4.50
$ 4.50
$ 4.50
How much?
$ 4.50
$ 4.50 $9 =
$4.50
per hour
$ 4.50
$ 4.50
2 hours $
hour =
4.50
$ 4.50
$ 4.50
$ 4.50
$ 4.50
$4.50
$ 4.50
$ 4.50
$ 9
$4.50
$4.50
$4.50
$ 4.50
2 hours
1 hour
17 hours
First, how much is each hour worth?
Then, how much are 17 hours worth?
b). Why do we multiply here? $
hour
4.50
• 17 hours
= $76.50

5. 3). If 6 lbs of noodles can serve 8 people, how many pounds would be needed for 14 people?=
0.75 lb
0.75
lb per person
0.75 lb
0.75 lb
8 people
0.75 lb lb
person
0.75 lb
0.75 lb =
0.75
0.75 lb
0.75 lb
0.75 lb
0.75 lb
0.75 lb
0.75 lb
0.75 lb
8 people
1 person
14 people
First, how much for each person?
Then, how much for 14 people? lb
person
0.75
• 14 people
= 10.5 lb

6. 4). How many gallons of gas would a U. S
4). How many gallons of gas would a U.S. Army tank use in driving 14 miles, since it uses
120 gallons to go 40 miles?
What we need to know first.
What we want to find out.
for each mile
Gallons for 14 miles
a). Can you explain this?
120
gallons 40
miles
gallons
gallons 3 3 •
14 miles
= 42 gallons
mile
mile
b). What does this
represent?
c). Can you explain this?

7. 5). How far could a U.S. Army tank go on 14 gallons of gas, since it uses 120 gallons to go 40 miles?
What we need to know first.
What we want to find out.
for each gallon
Miles for 14 gallons
40 miles
120 gallons
divide
miles
0.33 •
14 gallons
= miles
gallon
miles
0.33
gallon
rounded

8. Discussion How were #4 and #5 related? What was the same about them?
What did you have to do differently in them?

9. 3 laps in 4 minutes
6). You ran At that rate, far will you run in 11 minutes ?
When she started this problem, Alisha made a mistake.
for each minute
Laps for 11 minutes
This does not represent each minute.
What’s not correct?
4 minutes
3 laps
min.
1.33
lap