Visualising Common Denominators

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Learning Objective

At the end of the lesson you will be able to explain and use pictures to find a common denominator for fractions.

What do you already know about finding common denominators?

What Is a Denominator?

The denominator is the number below the fraction line. It shows how many equal parts make a whole.

Why Find a Common Denominator?

To add or compare fractions, their denominators must be the same. This makes the parts equal.

Pictorial Example – Different Denominators

Imagine 1/2 (one-half) and 1/3 (one-third). The sizes of the pieces are not equal yet. Let's see it!

Making Denominators the Same

We turn each shape into equal parts. For 1/2 and 1/3, we use 6 parts (sixths), so both pies are split into 6 slices.

Schematic Drawing – Step by Step

Draw two circles. Split one into 2, the other into 3. Then redraw both, splitting each into 6, so pieces match.

Practical Example: 2/5 and 1/2

Multiply 5 by 2 = 10. The common denominator is 10.

Show both fractions as tenths (2/5 = 4/10 and 1/2 = 5/10). Colour the parts to see the answer visually.

Step 2: Draw Fractions

Step 1: Find the Common Denominator

Summing Up

A common denominator helps compare or add fractions. Using drawings helps us see why and how this works.

Write down 3 things you learned in this lesson.

Write down 2 things you want to know more about.

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