Home›Lesson Plans›Mathematics›Precalculus · Grade 12

Polynomial & Rational Functions: End Behavior & Asymptotes

Students analyze the graphs of polynomial and rational functions — predicting end behavior from the degree and leading coefficient, and finding the asymptotes and zeros that define a rational function’s shape.

Grade 12Functions50 minutes1 class periodGradual ReleaseExplicit teaching4 StandardsCommon Core
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Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Predict end behavior.
  • ✓Find the zeros of a polynomial.
  • ✓Find vertical asymptotes.
  • ✓Relate degree to graph shape.
Essential Question

Just by glancing at a function’s equation, an expert can sketch where its graph rises, falls, and shoots to infinity. What clues make that possible?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Model · Interactive Tool

Analyze the Function

Project each item and have students predict end behavior, zeros, and asymptotes. The tool explains how degree and structure shape the graph.

📈 Analyze polynomial & rational functionsTry it
Analyze the behavior of polynomial and rational functions.
The Lesson · Gradual Release (I Do · We Do · You Do)

50 minutes, five moves

Tap any phase to open the teacher moves and student actions.

1

Launch — Read the Equation

5 min

How can an expert sketch a graph just from its equation?

👩‍🏫 Teacher Moves

  • Show a polynomial equation.
  • Ask what its graph does.
  • Set the goal: analyzing functions.

🎒 Student Actions

  • Read the equation.
  • Wonder about the graph.
  • Predict the shape.
2

I Do — Degree & Asymptotes

10 min

Teacher models.

👩‍🏫 Teacher Moves

  • End behavior from degree/leading coefficient.
  • Zeros from factors.
  • Vertical asymptotes from the denominator.

🎒 Student Actions

  • Learn end behavior.
  • Find zeros.
  • Find asymptotes.
3

We Do — Analyze Together

13 min

Class uses Analyze the Function.

👩‍🏫 Teacher Moves

  • Predict end behavior.
  • Locate zeros and asymptotes.
  • Sketch a rough graph.

🎒 Student Actions

  • Predict behavior.
  • Find features.
  • Sketch it.
4

You Do — On Your Own

12 min

Students analyze functions.

👩‍🏫 Teacher Moves

  • Analyze polynomials and rationals.
  • Find zeros and asymptotes.
  • Match equation to graph.

🎒 Student Actions

  • Analyze them.
  • Find features.
  • Match graphs.
5

Close — Close

5 min

One function.

👩‍🏫 Teacher Moves

  • Give a function to analyze.
  • State its key features.
  • Hand out the exit ticket.

🎒 Student Actions

  • Analyze it.
  • State features.
  • Complete the exit ticket.
Standards Alignment

Built to the standards you report on

Aligned to the Common Core State Standards for Mathematics (High School: Precalculus).

CCSS
F-IF.7c

Graph polynomial functions, identifying zeros and end behavior.

CCSS
F-IF.7d

Graph rational functions, identifying zeros and asymptotes.

CCSS
A-APR.3

Identify zeros of polynomials and use them to sketch a graph.

CCSS
A-APR.6

Rewrite rational expressions.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • End-behavior picture cards.
  • Sentence frame: “An asymptote is where ___.”
  • Match equation to graph.

Support & Access

IEP / 504
  • Focus on end behavior first.
  • Use degree to predict shape.
  • Provide worked examples.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Find horizontal asymptotes.
  • Analyze holes vs. asymptotes.
  • Sketch a full rational graph.
Materials

What to gather

  • 📽️Projector / board
  • 📓Math notebooks
  • 💻Analyze the Function
  • 📐Graph paper
  • 🧮Graphing calculators
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

polynomial functiona function of powers of xrational functiona ratio of two polynomialsdegreethe highest power in a polynomialleading coefficientthe coefficient of the highest termend behaviorwhat the graph does at the far endszeroan x-intercept (where y = 0)vertical asymptotea line the graph approaches but never crossesasymptotea line a graph approaches
Evaluate

Exit Ticket

Preview the three formative checks. Tap “Sample answer” to see what mastery looks like — hide them before you print for students.

QUESTION 1
Where does a rational function have a vertical asymptote?
Where the denominator equals zero (and the numerator does not).
QUESTION 2
What determines the end behavior of a polynomial?
Its degree (even or odd) and the sign of its leading coefficient.
QUESTION 3
At most how many real zeros can a degree-4 polynomial have?
4.

Going deeper? Horizontal asymptotes.

Have students determine horizontal asymptotes of rational functions by comparing the degrees of the numerator and denominator. A printable functions sheet is in the Math library.

Study · Flashcards

Study the key terms

Tap a card to flip it, then rate whether you knew it. Built from this lesson’s vocabulary.

🃏 Polynomial & Rational FunctionsFlip
Card 1
Term
Tap to flip →
Meaning
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Practice · Quiz

Check your understanding

A quick self-check with instant feedback, drawn from this lesson’s key terms.

📝 Polynomial & Rational FunctionsQuiz
Score: 0
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Question 1
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Practice · Worksheet

Printable worksheet

A print-and-go review sheet with a built-in answer key. Tap “Show answer key” to reveal answers, or print the clean version for students.

🖨️ Polynomial & Rational FunctionsPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: asymptote, degree, end behavior, leading coefficient, polynomial function, rational function, vertical asymptote, zero
  1. the highest power in a polynomial
  2. a line a graph approaches
  3. what the graph does at the far ends
  4. a ratio of two polynomials
  5. a line the graph approaches but never crosses
  6. a function of powers of x
  7. an x-intercept (where y = 0)
  8. the coefficient of the highest term

Part B · Show what you learned

  1. Where does a rational function have a vertical asymptote?
  2. What determines the end behavior of a polynomial?
  3. At most how many real zeros can a degree-4 polynomial have?
Answer key — Part A: 1) degree · 2) asymptote · 3) end behavior · 4) rational function · 5) vertical asymptote · 6) polynomial function · 7) zero · 8) leading coefficient
Part B: 1) Where the denominator equals zero (and the numerator does not). 2) Its degree (even or odd) and the sign of its leading coefficient. 3) 4.