← Back to Identifying Functions

Identifying Functions - Worksheet 3 - 8th Grade

Easy

Determine whether a relation is a function (Easy)

18 problems · 15-20 minutes · Skills: functions, vertical line test, relations

About This Worksheet

This easy-level worksheet contains 18 problems designed for 8th Grade students practicing identifying functions. Easy worksheets use simpler numbers and straightforward problem types to build confidence and reinforce foundational skills.

Determining whether a relation is a function is a gatekeeping skill in mathematics. Every subsequent topic — graphing, modeling, calculus — assumes the ability to recognize and work with functional relationships.

  • Use the vertical line test to determine if a graph represents a function
  • Identify functions from tables by checking for repeated inputs with different outputs
  • Use mapping diagrams to analyze whether a relation is a function
  • Give a counterexample to show why a relation fails to be a function
  • Classify real-world relationships as functions or non-functions with justification

How to Solve: Worked Example

Example Problem: Solve the first problem on the worksheet.
Solution Steps:
  1. Read the problem carefully.
  2. Identify what is being asked.
  3. Use what you know to find the answer.
  4. Check your work.
Answer: See the answer key below
Tip: Take your time and read each problem carefully before answering!
1
1 + 2 =
2
4 + 3 =
3
1 + 2 =
4
3 + 2 =
5
3 + 5 =
6
1 + 5 =
7
4 + 3 =
8
1 + 1 =
9
2 + 1 =
10
4 + 5 =
11
4 + 4 =
12
3 + 4 =
13
1 + 3 =
14
2 + 2 =
15
3 + 2 =
16
4 + 2 =
17
5 + 2 =
18
4 + 3 =

Answer Key

1. 32. 73. 34. 55. 86. 67. 78. 29. 310. 911. 812. 713. 414. 415. 516. 617. 718. 7

Frequently Asked Questions

How do I download this identifying functions - worksheet 3 worksheet?

Click the "Download PDF / Print" button at the top of the worksheet. You can save it as a PDF or print it directly. The answer key will be on a separate page.

How do I find worksheets at different difficulty levels?

Each subtopic has 10 worksheets: Worksheets 1-3 are Easy, 4-7 are Medium, and 8-10 are Hard. Start with Easy worksheets to build confidence, then progress to harder ones.

What skills does this functions worksheet cover?

This worksheet focuses on functions, vertical line test, relations. It is designed for 8th Grade students and provides structured practice through varied problem types with a worked example to guide students before they begin.

Can I use this worksheet in my classroom?

Yes. All worksheets on K12Worksheets are free for classroom use. You can print copies for your entire class. With 10 worksheets per subtopic at three difficulty levels, you have plenty of options for differentiated instruction and individualized practice.

How many problems are on this worksheet?

This worksheet contains 18 problems. It typically takes 15-20 minutes to complete. An answer key with all solutions is included so parents and teachers can check work quickly.