LESSON 5 Problems of Scale

Luis and his father are building a dollhouse for Luis's little sister. Luis noticed that the directions said that 3 centimeters on the dollhouse is equal to 1 foot in a real house. His father explained that this means that the dollhouse is a scale model of a real house. A scale model is a representation or copy of an object that can be larger or smaller than the actual size of the object. In a scale model, the ratio between the size of the parts in the model and the size of the actual parts of the object remain equal.

Luis is putting windows in the living room of the dollhouse. Each living room window is 12 centimeters tall and 6 centimeters wide. He wondered what size the window would be in a real house. He decided to start by writing a ratio to show the scale for the dollhouse model.

Then Luis wrote a number sentence to find the height of the window in a real house.

Work with your partner to decide how Luis can find the actual length that each window would be in the real house.
Explain how you can use equivalent ratios to find the width that each window would be in a real house. Write a number sentence to show how you solved this problem.