5th Grade Math Lesson

Baking with Broken Denominators: Adding & Subtracting Fractions with Unlike Denominators

Shared by A STEM Educator

5th GradeThinking Classroom45 min

Learning Objective

Students will add and subtract fractions with unlike denominators by finding a common denominator, creating equivalent fractions, and simplifying results, including mixed numbers.

Lesson Overview

Students discover how to add and subtract fractions with unlike denominators through a baking context, progressing from visual area-model representations on grid paper to multi-step mixed-number problems. Tasks thin-slice from same-denominator review through ceiling-level multi-fraction word problems.

Materials

Vertical whiteboards or large chart paper
Dry-erase markers (multiple colors if available)
Pencils and blank paper for grid drawing
Random grouping cards or a quick method to assign groups of 2-3

Scaffolded Task Progression

1Task 1

A recipe needs

\frac{2}{6}

cup of oats and

\frac{3}{6}

cup of flour. How much dry ingredient is that in total?

On your whiteboard, draw a rectangle divided into 6 equal columns. Shade

2

columns one color and

3

columns another color. Write the addition sentence and the answer.

2Task 2

A recipe needs

\frac{1}{4}

cup of cocoa powder and

\frac{2}{4}

cup of sugar. How much is that altogether?

Write the addition sentence. Can you simplify your answer?

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