CCSS.Math.Content.8.F.A
The standard
Define, evaluate, and compare functions.
Common Core State Standards for Mathematics
What this standard means
Students need to recognize when a rule, table, graph, or verbal situation gives exactly one output for each input. They also need to find outputs from a given input, use function notation when expected, and compare two relationships shown in different forms.
Mastery looks like moving easily between words, tables, equations, and graphs. Students can explain which relationship has a greater rate of change or starting value, and justify with numbers. Common trouble spots are mixing up input and output, thinking every graph is a function, and comparing only one point instead of the pattern.
Ways to teach it
- Give pairs cards with tables, graphs, equations, and situations, then have them sort into functions and not functions with a reason for each.
- Ask students to write: How can you tell if a table, graph, or story represents a function?
- Show an equation and a table, then ask students to find f(3) or the output when x equals 3 on a sticky note.
- Compare two phone plans shown as a graph and an equation, then decide which costs less after 10 gigabytes.
Plan a lesson for CCSS.Math.Content.8.F.A
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Related standards
- CCSS.Math.Content.HSF-IF.A.2
Use function notation, evaluate functions for inputs in their domains, and interpret statements that use function notation in terms of a context.
- CCSS.Math.Content.HSF-IF.C.9
Compare properties of two functions each represented in a different way (algebraically, graphically, numerically in tables, or by verbal descriptions).
- CCSS.Math.Content.8.F.A.2
Compare properties of two functions each represented in a different way (algebraically, graphically, numerically in tables, or by verbal descriptions).
- CCSS.Math.Content.HSF-IF.C
Analyze functions using different representations