Home›Lesson Plans›Mathematics›Number & Operations—Fractions · Grade 4

Adding & Subtracting Fractions: Same Bottom, Add the Top

Students add and subtract fractions with the same denominator and discover the simple rule — when the bottom numbers match, you just combine the tops.

Grade 4Fractions45 minutes1 class periodGradual ReleaseExplicit teaching4 StandardsCommon Core
Start the Lesson
Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Add fractions with the same denominator.
  • ✓Subtract fractions with the same denominator.
  • ✓Explain why the denominator stays the same.
  • ✓Solve fraction word problems.
Essential Question

You eat 2/8 of a pizza and your friend eats 3/8. How much is gone — and why doesn’t the bottom number change?

0
Lesson Phases
0
Vocabulary Terms
0
Standards Aligned
0
Interactive Task
Model · Interactive Tool

Add the Fractions

Project this and set two fractions with the same bottom number. Watch the shaded parts combine, and see why the denominator doesn’t change.

➕ Combine two fractions — same denominatorTry it
First fraction (top number)1
Second fraction (top number)2
Denominator (bottom number)6

The Lesson · Gradual Release (I Do · We Do · You Do)

45 minutes, five moves

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

1

Launch — Two Slices

5 min

2/8 of a pizza plus 3/8 — how much pizza?

👩‍🏫 Teacher Moves

  • Pose the pizza problem.
  • Ask what to do with the numbers.
  • Set the goal: adding fractions.

🎒 Student Actions

  • Picture the pizza slices.
  • Predict the total.
  • Guess the rule.
2

I Do — Add the Tops

10 min

Teacher models with bars.

👩‍🏫 Teacher Moves

  • Show 2/8 + 3/8 with fraction bars.
  • Add the tops; keep the bottom.
  • Do a subtraction example too.

🎒 Student Actions

  • Watch the bars combine.
  • Add the tops.
  • See the bottom stay.
3

We Do — Combine Together

12 min

Class drives the tool.

👩‍🏫 Teacher Moves

  • Use Add the Fractions with the class.
  • Try sums that pass one whole.
  • Explain the denominator staying.

🎒 Student Actions

  • Set fractions to add.
  • Read the sum.
  • Explain the bottom.
4

You Do — On Your Own

13 min

Students add and subtract.

👩‍🏫 Teacher Moves

  • Assign add/subtract with like denominators.
  • Include a word problem.
  • Watch for changing the denominator.

🎒 Student Actions

  • Add and subtract fractions.
  • Solve a word problem.
  • Keep the denominator.
5

Close — Close

5 min

Back to the pizza.

👩‍🏫 Teacher Moves

  • Return to 2/8 + 3/8.
  • Have students solve it.
  • Hand out the exit ticket.

🎒 Student Actions

  • Solve 2/8 + 3/8 = 5/8.
  • Explain the bottom.
  • Complete the exit ticket.
Standards Alignment

Built to the standards you report on

Aligned to the Common Core State Standards for Mathematics, including the Standards for Mathematical Practice.

CCSS
4.NF.3

Understand addition and subtraction of fractions as joining and separating parts referring to the same whole.

CCSS
4.NF.3a

Add and subtract fractions with like denominators.

CCSS
4.NF.3d

Solve word problems involving addition and subtraction of fractions.

SMP
MP.4

Model with mathematics using fraction bars.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Fraction strips to combine.
  • Sentence frame: “___/___ + ___/___ = ___/___.”
  • Say “add the tops, keep the bottom.”

Support & Access

IEP / 504
  • Use denominators of 4 or fewer parts first.
  • Provide fraction bars to shade.
  • Focus on adding before subtracting.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Add fractions that make more than one whole.
  • Add a fraction and a whole number.
  • Subtract fractions with regrouping.
Materials

What to gather

  • 📽️Projector / board
  • 📓Math notebooks
  • 💻Add the Fractions
  • 📏Fraction strips
  • ✏️Colored pencils
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

fractiona number of equal partsnumeratorthe top number — parts you havedenominatorthe bottom number — total partsaddto join amounts togethersubtractto take an amount awaysumthe answer to additionlike denominatorsthe same bottom numberwholeone complete unit
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
Solve: 3/6 + 2/6.
5/6 (add the tops, keep the bottom).
QUESTION 2
Solve: 5/8 − 2/8.
3/8.
QUESTION 3
When you add fractions with the same denominator, why doesn’t the bottom number change?
Because the parts are the same size — you’re just counting how many of those equal parts you have, so only the top number changes.

Going deeper? Fraction number line.

Have students add and subtract fractions by hopping along a fraction number line, landing on each sum. A printable fraction number line 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.

🃏 Adding & Subtracting FractionsFlip
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.

📝 Adding & Subtracting FractionsQuiz
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.

🖨️ Adding & Subtracting FractionsPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: add, denominator, fraction, like denominators, numerator, subtract, sum, whole
  1. the bottom number — total parts
  2. the same bottom number
  3. to take an amount away
  4. the answer to addition
  5. one complete unit
  6. the top number — parts you have
  7. a number of equal parts
  8. to join amounts together

Part B · Show what you learned

  1. Solve: 3/6 + 2/6.
  2. Solve: 5/8 − 2/8.
  3. When you add fractions with the same denominator, why doesn’t the bottom number change?
Answer key — Part A: 1) denominator · 2) like denominators · 3) subtract · 4) sum · 5) whole · 6) numerator · 7) fraction · 8) add
Part B: 1) 5/6 (add the tops, keep the bottom). 2) 3/8. 3) Because the parts are the same size — you’re just counting how many of those equal parts you have, so only the top number changes.