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8th grade Is it a function? Inputs, outputs, domain and range worksheet

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Is it a function? Inputs, outputs, domain and range

Grade 8 Math Worksheet - Challenge Me

NameDate

Circle the best answer, or write your answer on the line.

  1. Read this first

    Use the table

    input: xoutput: y
    -25
    1/23
    4-1
    -25
    33
    60

  2. Ren copies a rule table from the board and writes one row twice. Is it a function, and why?

    • Yes: inputs -2, 1/2, 3, 4 and 6 each have one output
    • No: the outputs do not change by the same amount each time
    • No: input -2 appears in two rows

  3. (-7, 3), (2, -4), (5, 3), (2, -4), (-1, 0), (8, 6). Ari collects points from three classmates, and two of them sent the same one. Is it a function, and why?

    • No: input 2 appears in two pairs
    • No: inputs -7 and 5 share the output 3
    • Yes: inputs -7, -1, 2, 5 and 8 each have one output

  4. (3, 1/2), (-2, 4), (3, 2), (6, 4), (0, -3). Bo writes points for a grid design of a kite. Is it a function, and why?

    • No: inputs -2 and 6 share the output 4
    • Yes: inputs -2, 0, 3 and 6 each have an output
    • No: input 3 has two outputs, 1/2 and 2

  5. (4, -2), (-3, 5), (4, -2), (1, 0), (-3, 6). Two inputs repeat in Esme's list of points. One repeat is harmless; one is not. Is it a function, and why?

    • No: input 4 appears in two pairs
    • No: input -3 has two outputs, 5 and 6
    • Yes: inputs -3, 1 and 4 each have an output

  6. Kira plots a zigzag path for a toy car race on a grid. Is it a function, and why?

    • Yes: inputs -5, -3, 0, 1, 3 and 5 each have one point
    • No: (-3, -1) and (1, -1) are at the same height
    • No: the points are not on one straight line

  7. The pond was 14°C at 9 a.m., 19°C at noon and 14°C at 6 p.m. Milo makes temperature the input and time the output. Is it a function, and why?

    • No: 14°C goes with two times, 9 a.m. and 6 p.m.
    • No: the times are not evenly spaced, so the rule fails
    • Yes: every temperature has a time

  8. On a winter day it was -2°C at 6 a.m., 5°C at noon and -2°C at 9 p.m. Noah makes time the input and temperature the output. Is it a function, and why?

    • Yes: each time has just one temperature
    • No: 6 a.m. and 9 p.m. share -2°C
    • No: the temperature goes up, then comes back down

  9. Pia scans library books: barcodes 104 and 117 are two copies of Comet Kids, and 125 is Sea Maps. Input: barcode. Output: title. Is it a function, and why?

    • Yes: no title appears twice
    • Yes: each barcode has just one title
    • No: barcodes 104 and 117 share a title

  10. Ari plots points for a robot's path, and the robot got confused. This graph is not a function. Which input has two different outputs?

  11. Jun's pairs make a function: (1, 4), (3, 6), (5, 4), (6, 9). Which new pair can join and keep it a function?

    • (3, 8)
    • (5, 1)
    • (2, 6)
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8th grade Is it a function? Inputs, outputs, domain and range worksheet – printable
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About this worksheet

Is it a function? Inputs, outputs, domain and range. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can tell whether a table, a list of pairs, a mapping, a graph of points or a story is a function: every input has exactly one output.
  • I can list the domain (inputs) and range (outputs), each value once, and say which amount is the input (independent variable).

Standard: 8.F.A.1

Words to know

input: The number or thing you start with: the first column, the first number in a pair.

output: What the input gives you: the second column, the second number in a pair.

function: A rule where every input has exactly one output.

mapping: Arrows from inputs to outputs. Each arrow is one row of the table.

domain / range: Every input / every output, each listed once.

independent / dependent variable: The input you choose / the output that depends on it.

up-and-down line: A vertical line on a graph. Two points on one share an input.

Common mistakes

Your child said a relationship is not a function because two inputs share an output. That is allowed.

Your child checked that every input has an output but missed an input that has two different outputs. Try sorting the rows by input together and looking for repeats.

Your child saw the same input twice and called it a problem, but both times it had the same output.

What to say

Ask: does any one input get two different outputs?

Ask: when an input repeats, are its outputs the same or different?

Questions parents ask

What is the most common mistake with is it a function? inputs, outputs, domain and range?

Your child said a relationship is not a function because two inputs share an output. That is allowed.

How can I help my child with is it a function? inputs, outputs, domain and range?

Ask: does any one input get two different outputs?

Are these 8th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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