8.5.G
The Standard
identify functions using sets of ordered pairs, tables, mappings, and graphs
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students decide whether a relation assigns exactly one output to each input. They check repeated inputs, mapping arrows, table rows, and vertical lines through graphs.
What Mastery Looks Like
- Students correctly classify relations in all four forms and cite clear evidence. They recognize that outputs may repeat, but each input must have only one output.
Common Misconceptions
- Students often think repeated outputs mean a relation is not a function. They may confuse the vertical line test with a horizontal line test or overlook one input pointing to two outputs.
How to Assess It
- Exit ticket: Decide whether {(1, 4), (2, 4), (1, 5)} is a function, then name the ordered pairs that prove your answer.
Lesson moves
Ways to Teach It
Connect labeled input and output cards with yarn, then inspect whether any input card connects to more than one output.
Compare {(1, 3), (2, 3)} and {(1, 3), (1, 4)}, then write why only one is a function.
Play a four-corners sort using relation cards labeled function, not a function, unsure, and need another representation.
Test real examples such as student to birth month and birth month to student, then explain which direction makes a function.
Keep exploring
Related Standards
- 5.8.C
graph in the first quadrant of the coordinate plane ordered pairs of numbers arising from mathematical and real-world problems, including those generated by num...
- 7.6.G
solve problems using data represented in bar graphs, dot plots, and circle graphs, including part-to-whole and part-to-part comparisons and equivalents;
- 6.6.A
identify independent and dependent quantities from tables and graphs
- 3.5.E
represent real-world relationships using number pairs in a table and verbal descriptions
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