7th Grade Math
Lesson Objective:
Students will identify proportional and
nonproportional relationships.
Vocabulary
 Proportional
 Two quantities that have a constant ratio
 Example:
8 16
16 = 16
1 2
 Nonproportional
 Two quantities that do NOT have a constant
ratio
 Example: 10 17
17 ≠ 20
1 2
Identifying Proportional
Relationships - Tables

Kudzu is a vine that grows an average of
7.5 feet every 5 days. Is the number of
days of growth proportional to the length
of the vine as measured on the last day?
Length
7.5
15
22.5
30
# of Days
5
10
15
20
7 .5
 1 .5
5
15
 1 .5
10
22.5
30
 1 .5
 1 .5
15
20
Yes
Identifying Proportional
Relationships - Tables

The Vista Marina rents boats for $25 per
hour. In addition to the rental fee, there is
a $12 charge for fuel. Is the number of
hours you can rent the boat proportional
to the total cost?
Total Cost
37
62
87
112
Hours
1
2
3
4
37
 37
1
87
62
 29
 31
3
2
No
112
 28
4
Identifying Proportional
Relationships – Cross Products

Ms. Cochran is planning a year-end pizza
party for her students. Ace Pizza offers
free delivery and charges $8 for each
medium pizza. Is the cost of an order
proportional to the number of pizzas
ordered?
cost of order
# of pizzas
8
1
16
2
16 = 16
Yes
Identifying Proportional
Relationships – Cross Products

Uptown Pizzeria sells medium pizzas for
$7 each but charges a $3 delivery fee per
order. Is the cost of an order proportional
to the number of pizzas ordered?
cost of order 10
# of pizzas 1
17
2
17 ≠ 20
No