This document contains notes from a math lesson on identifying proportional and non-proportional relationships in graphs. It includes examples of filling in tables with proportional values and plotting those points on a graph. It emphasizes that for quantities to be proportional, their graph must be a straight line passing through the origin. The closing questions review that proportional relationships are represented by graphs with points on a line through the origin, and that a common mistake is thinking quantities are proportional if their graph is a straight line but does not pass through the origin.

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Identifying Proportional and
Non-Proportional Relationships in Graphs
Homework: Lesson #5 Problem Set/Quiz 1 Friday
Do Now: Check Lesson #4 Problem Set
09/18/13
Module 1, Lesson 5

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Problem Set Solutions (continued)

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Lesson 4 Exit Ticket Review

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x
y
Fill in the table below so that y is
proportional to x.

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Important Note:
Characteristics of graphs of proportional relationships:
1. Points lie in a straight line.
2. Line goes through the origin.

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x
y
Plot ordered pairs for all the values of
the Opening Exercise.

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x
y

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Compare Example 1 and Example 3
x
y
x
y

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Closing Questions
1. How are proportional quantities represented in a
graph?
They are represented in a graph where the points lie on a straight
line that passes through the origin.
2. What is a common mistake a student might make
when deciding whether a graph of two quantities
shows that they are proportional to each other?
Both graphs can have points that lie on a straight line, but the graph
of the quantities that are proportional to each other also goes through
the origin. In addition the graph could go through the origin, but the
points do not lie on a straight line.

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