Scaling with Fractions

Contributor: Ashley Nail. Lesson ID: 13889

Have you ever wondered how to reduce or enlarge the size of something? Did you ever think multiplying could do both? Well, it depends on what type of fraction you multiply by!

categories

Fractions and Operations, Modeling

subject
Math
learning style
Visual
personality style
Lion, Otter, Beaver, Golden Retriever
Grade Level
Intermediate (3-5)
Lesson Type
Quick Query

Lesson Plan - Get It!

Audio:

Declan is working on a project for his art class. His group has to make a tiny model of a kitchen.

tiny kitchen model

Declan’s art teacher told his group that the carrots are too big and not made to scale. The teacher explains that scale means the size of the carrots needs to be accurate but reduced or enlarged.

Declan measures the carrots as 11/16 of an inch and knows they need to be resized to be smaller.

  • Should he multiply the measurement by 9/8, 3/3, or by ¼?
  • Which amount will reduce the size of the carrots?

Before we resize the carrots, let’s look at an example of resizing using different fractions.

Look at the fork below, which measures 3/5 of an inch:

one fork

  • What happens when we multiply this measurement by different fractions?

Look at the three multiplication expressions we can use to resize the fork (below).

  • Can you predict which expression will enlarge the size of the fork?
  • Which one will reduce the size of the fork?

resizing equations

First, let’s look at the expression in green.

We can break the fraction into 3/5 x 2/2. We know that 2/2 can be simplified into the whole number of 1, which changes the expression to 3/5 x 1.

green equation

Without calculating the expression, we can assume the size of the fork will stay the same since it is multiplied by 1.

green equation size

Next, let’s look at the pink expression.

2/3 is less than 1, which means we will scale down the size of the fork. Or, in other words, the product of 3/5 x 2/3 will be less than 3/5.

Last, let’s look at the red expression.

3/2 is greater than 1, which means we will scale up the size of the fork. Or, in other words, the product of 3/5 x 3/2 will be greater than 3/5.

We just resized the fork by multiplying the original number by different types of fractions!

Let’s review what we just learned!

When you are ready, click NEXT to visit the Got It? section to practice on your own!

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