Vertical Line Test Printable | Grade 8 Math

This Grade 8 math worksheet builds students' ability to determine whether a graph represents a function by applying the vertical line test across 12 structured problems. Students analyze coordinate plane graphs, draw vertical lines, and record whether each relation qualifies as a function—developing the conceptual foundation required by CCSS.MATH.CONTENT.8.F.A.1.

At a Glance

• Grade: 8 · Subject: Math
• Standard: CCSS.MATH.CONTENT.8.F.A.1 — Understand that a function assigns exactly one output to each input
• Skill Focus: Applying the vertical line test to graphs of relations
• Format: 4 pages · 12 problems · Answer key included · PDF
• Best For: Guided or independent functions practice
• Time: 20–30 minutes

The worksheet spans four pages and presents 12 coordinate plane graphs depicting various relations—including linear, curved, circular, and irregular graphs. Students apply the vertical line test to each graph and identify the relation as a function or not a function, recording their answers in clearly labeled response spaces. A complete answer key is included so teachers can use it for self-checking or whole-class review.

Skill Progression

• Guided practice (Problems 1–4): Graphs are straightforward—simple lines and basic curves—allowing students to build confidence with the vertical line test using recognizable function forms.
• Supported practice (Problems 5–8): Graphs increase in complexity, introducing parabolas, absolute value shapes, and relations that cross a vertical line at two points, requiring students to reason more carefully.
• Independent practice (Problems 9–12): Students encounter irregular curves, circles, and multi-valued relations with no scaffolding, applying the test independently to confirm mastery. This gradual-release structure mirrors the I Do, We Do, You Do model.

Standards Alignment

The primary standard is CCSS.MATH.CONTENT.8.F.A.1: Understand that a function is a rule that assigns to each input exactly one output. A supporting connection exists with CCSS.MATH.CONTENT.8.F.A.2, as comparing functional and non-functional graphs lays groundwork for comparing properties of two functions.

How to Use It

Use Problems 1–4 during direct instruction as a whole-class check-for-understanding immediately after modeling the vertical line test on the board. Then assign Problems 5–12 as independent practice or homework. As students work, observe whether they are drawing the vertical line at multiple x-values or only at one—this reveals whether they understand the test as a universal check rather than a single-point check, a common Grade 8 misconception. Most students complete the full worksheet in 20–30 minutes.

Who It's For

This worksheet is designed for Grade 8 students beginning the functions unit. It works well for on-level learners and can support students who need repeated visual exposure to the function definition. Pair it with a coordinate plane anchor chart showing labeled examples of functions and non-functions to reinforce vocabulary alongside the procedural skill.

Aligned to CCSS.MATH.CONTENT.8.F.A.1, this resource targets a foundational Grade 8 skill. Research supports structured, graph-based tasks for building conceptual understanding of functions. The included answer key allows teachers to provide immediate corrective feedback, a practice linked to stronger concept formation. The worksheet is suitable for whole-class instruction, small-group intervention, or independent review, and its PDF format makes it ready to print without additional preparation.