Georgia 8.FGR.5.1
The Standard
Show and explain that a function is a rule that assigns to each input exactly one output.
Georgia's K-12 Mathematics Standards · Describe the properties of functions to define, evaluate, and compare relationships, and use functions and graphs of functions to model and explain real phenomena.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students decide whether a relation represents a function. They check whether any input is paired with more than one result and explain their reasoning using the representation shown.
What Mastery Looks Like
- Students correctly classify relations shown as tables, ordered pairs, mappings, graphs, or rules. They identify a repeated input with different results and use it to justify their decision.
Common Misconceptions
- Students may think repeated outputs make a relation invalid, even when the inputs differ. They may also miss repeated inputs in unordered tables or misapply the vertical line test.
How to Assess It
- Give students the relation {(1, 4), (2, 5), (1, 6)}. Ask, “Is it a function? Circle the evidence and explain in one sentence.”
Lesson moves
Ways to Teach It
Give students input and output cards, have them form mappings, then test whether one input card connects to two different outputs.
Ask students to explain why two students can share a birthday, but one student cannot have two different birthdays.
Run a function sort relay using cards with tables, graphs, ordered pairs, and mapping diagrams, requiring a written reason for each choice.
Compare vending machine buttons and products, then discuss whether a machine giving different products for the same button follows a function rule.
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Printable 8.FGR.5.1 Worksheet
A ready-to-print activity worksheet aligned to 8.FGR.5.1, with an answer key for the teacher on its own page. No account needed.
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Related Standards
- 8.FGR.5.6
Write a linear function defined by an expression in different but equivalent forms to reveal and explain different properties of the function.
- 8.PAR.4.2
Show and explain that the graph of an equation representing an applicable situation in two variables is the set of all its solutions plotted in the coordinate p...
- 5.PAR.6
Solve relevant problems by creating and analyzing numerical patterns using the given rule(s).
- 4.PAR.3.2
Use input-output rules, tables, and charts to represent and describe patterns, find relationships, and solve problems.
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