Maryland Math 8.AT.C.6.a
The Standard
- 8.AT.C.6
- Determine whether a relationship is a function by analyzing whether each input is assigned to exactly one output.
Given a clearly defined set of input-output pairs in a table, mapping, or real-world description, determine whether the relationship is a function and explain why.
Maryland College and Career Ready Standards for Mathematics (2025) · REASON ABOUT FUNCTIONS.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students read input and output pairs from a table, mapping, or short situation. They check whether any input has two different outputs, then explain their decision using the pairs.
What Mastery Looks Like
- A student points to (2, 5) and (2, 8) as proof a relationship is not a function. They accept (2, 5) and (3, 5) because different inputs can share an output.
Common Misconceptions
- Students may think a repeated output makes a relationship fail. They may miss a repeated input in a table or read the arrows in a mapping backward.
How to Assess It
- Exit ticket: For {(1, 4), (2, 4), (1, 5)}, decide whether the relationship is a function and name the pairs that prove your answer.
Lesson moves
Ways to Teach It
Give students input-output pairs on index cards; have them group cards by input and flag any input with two different outputs.
Show a mapping where 2 and 3 both point to 7; ask, 'Does sharing an output make it not a function? Why?'
Play Function or Not: flash a four-row table each round; partners vote and name the input that decides it.
Show a cafeteria price list with item codes and prices; have students check whether each code has one price.
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Printable 8.AT.C.6.a Worksheet
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Related Standards
- 8.AT.C.6
Determine whether a relationship is a function by analyzing whether each input is assigned to exactly one output.
- 8.AT.C.8
Identify whether a function is linear or non-linear given equations, graphs, or input-output pairs, and provide a justification using reasoning about the consta...
- 8.AT.D.10.a
Given two input-output pairs, a graph, a table, or a description of a relationship, determine the rate of change and initial value and write the linear equation...
- 8.AT.C.6.b
Given a graph, identify input-output pairs and determine whether the graph represents a function.
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