NY Next Generation Math NY-8.F.1

Math8th GradeDefine, evaluate, and compare functions.

The Standard

Understand that a function is a rule that assigns to each input exactly one output. The graph of a function is the set of ordered pairs consisting of an input and the corresponding output.

New York State Next Generation Mathematics Learning Standards

Teacher's field guide

What This Standard Means

What Students Need to Do

Students decide whether a rule assigns exactly one output to every input. They connect that rule to tables, mapping diagrams, ordered pairs, and graphs.

What Mastery Looks Like

A student recognizes that repeated outputs are allowed but one input cannot have two different outputs. On a graph, the student checks that each x-value appears with only one y-value.

Common Misconceptions

Students may think repeated y-values make a relation fail or overlook one input paired with two outputs. They may also treat every plotted collection as a function.

How to Assess It

Give students {(1, 4), (2, 4), (3, 5)} and {(1, 4), (1, 5), (2, 6)}. Ask which relation is a function and why.

Lesson moves

Ways to Teach It

  1. Use input and output cards to build a human mapping diagram, then test whether each input student points to one output.

  2. Ask students whether two inputs can share one output and still make a function, requiring an example in the explanation.

  3. Play a sorting game with relation cards shown as tables, graphs, and ordered pairs, placing each under function or not a function.

  4. Match each hour of a school day to the classroom temperature, then explain why time acts as the input.

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Printable NY-8.F.1 Worksheet

Preview of the NY-8.F.1 printable worksheet

A ready-to-print activity worksheet aligned to NY-8.F.1, with an answer key for the teacher on its own page. No account needed.

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