Grade 8 · Math

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

NameDate

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

Read this first
Use the table
input: hours after noon output: temperature in °C
7 3
2 8
5 6
9 3
4 10
1.
On a chilly day, Ren reads the thermometer at different hours after noon. Is it a function, and why?
- Yes: inputs 2, 4, 5, 7 and 9 each have one output
- No: the outputs do not change by the same amount
- No: inputs 7 and 9 share the output 3
2.
At an ice cream cart, Tala writes the people in line and the minutes waited, over two sunny days. Is it a function, and why?
- Yes: inputs 1, 3, 6 and 8 each have an output
- No: input 3 has two outputs, 9 and 11
- No: input 6 has two outputs, 14 and 20
3.
Ari draws a mapping for math club, and the arrows look like spaghetti. Is it a function, and why?
- Yes: inputs -3, 0 and 2 each send an arrow
- No: input 0 sends arrows to 2 and 5
- No: input -3 sends arrows to 4 and 2
4.
Esme checks a classmate's mapping before it goes on the wall. Is it a function, and why?
- No: input 4 sends arrows to 2 and 9
- Yes: inputs 1, 4, 6 and 8 each send an arrow
- No: inputs 1 and 6 both send an arrow to 7
5.
Noah plots points from a math club rule card. The rule card has a juice stain on it, but the points are clear. Is it a function, and why?
- No: the points are not on one straight line
- Yes: inputs -3, -1, 0, 2 and 4 each have one point
- No: (-1, -1) and (2, -1) are at the same height
6.
In a video game level, Pia plots where four stars sit on the grid. Is it a function, and why?
- Yes: inputs -4, -2, 1 and 3 each have one point
- No: the points are not on one straight line
- Yes: the points are evenly spaced along the grid
7.
In Zee's bike rack, bike 3 has 7 gears, bike 8 has 21 and bike 12 has 7. Input: bike number. Output: gears. Is it a function, and why?
- Yes: no gear count appears twice
- Yes: each bike has just one gear count
- No: bikes 3 and 12 share a gear count
Esme plots the stars in a game level. What is the range (all the outputs)? List each value once.
9.
Milo prints a 12-page comic. The more pages, the longer the printing takes. Which amount is the input (independent variable)?
- The input is the printing time
- The input is the printer
- The input is the number of pages
10.
Noah bakes cookies, 15 on each tray. The number of cookies depends on the number of trays. Which amount is the input (independent variable)?
- The input is the oven
- The input is the number of cookies
- The input is the number of trays

input: hours after noon	output: temperature in °C
7	3
2	8
5	6
9	3
4	10

8th grade Is it a function? Inputs, outputs, domain and range worksheet – printable — Print: 1 2 3 4 5 6

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.

More grade 8 math

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