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
Start the Lesson
Assign or share this lesson

Copy link works with Canvas, Schoology, Moodle and any other LMS — paste it in as a resource or assignment.

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?

0
Lesson Phases
0
Vocabulary Terms
0
Standards Aligned
0
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
0

Nice work!

Practice · Quiz

Check your understanding

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

📝 Polynomial & Rational FunctionsQuiz
Score: 0
1 / 6
Question 1
0%

Nice work!

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.