CCSS.Math.Content.7.RP.A.2c
The Standard
Represent proportional relationships by equations.
Common Core State Standards for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students identify the two changing quantities and find the constant rate connecting them. They write an equation in the form y = kx and explain what the variables and coefficient mean.
What Mastery Looks Like
- Given a table, graph, or situation, students find the unit rate and write an equation in the form y = kx. They define each variable, include units, and use the equation to find unknown values.
Common Misconceptions
- Students may write an additive equation, such as y = x + k, instead of multiplying by the constant rate. They may reverse the variables, treat one data pair as the rate, or miss that a proportional relationship starts at zero.
How to Assess It
- Give this exit ticket: “Three notebooks cost $7.50. At the same price per notebook, write an equation for cost c and number n, then find the cost of eight notebooks.”
Lesson moves
Ways to Teach It
Fill paper bags with four counters each, record bags and counters in a table, then write and test the equation c = 4b.
Discuss which equation fits “three stickers per page,” y = 3x or y = x + 3, and justify the choice in writing.
Play an equation match game using cards with situations, tables, graphs, and equations, then explain every completed set to a partner.
Use grocery ads to choose a unit price, define variables, write a total cost equation, and calculate the cost of several quantities.
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Printable 7.RP.A.2c Worksheet
A ready-to-print activity worksheet aligned to CCSS.Math.Content.7.RP.A.2c, with an answer key for the teacher on its own page. No account needed.
PDF, US Letter, prints cleanly in black and white.
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Where This Standard Sits
Before This Standard
If students are struggling here, check these first.
- CCSS.Math.Content.6.EE.C.9
Using variables for related quantities and linking tables or graphs to equations supports writing proportional equations like y = kx.
- CCSS.Math.Content.7.RP.A.2b
Writing y = kx depends on finding the constant of proportionality from tables, graphs, diagrams, or descriptions.
- CCSS.Math.Content.6.RP.A.2
Writing y = kx depends on understanding k as the unit rate that links each pair of proportional quantities.
Keep exploring
Related Standards
- CCSS.Math.Content.7.RP.A.2
Recognize and represent proportional relationships between quantities.
- CCSS.Math.Content.8.EE.B.5
Graph proportional relationships, interpreting the unit rate as the slope of the graph. Compare two different proportional relationships represented in differen...
- CCSS.Math.Content.7.RP.A.2a
Decide whether two quantities are in a proportional relationship, e.g., by testing for equivalent ratios in a table or graphing on a coordinate plane and observ...
- CCSS.Math.Content.7.RP.A.3
Use proportional relationships to solve multistep ratio and percent problems.
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