Starter Activity: Mr. Huynh

Ratios: Lesson Objectives WALT: WhatAmLearningToday Identify simple ratios Write ratios in their simplest form Use ratios to find fractions of amounts Determine equivalent ratios WILF: WhatImLookingFor How to identify and write simple ratios How to use ratios to find fractions of amounts and their equivalences.

DO NOW (not later): Compare the number of boys to girls in the class.

The number of boys = The number of girls = If we compare boys to girls we get ___ boys to _____ girls.

What do we call a comparison between two or more quantities? We just found the RATIO of boys to girls. RATIO Is the ratio of girls to boys the same ? No, when writing a ratio, ORDER matters.

How many basketballs to footballs are there? For every 4 basketballs there are 6 footballs. The ratio is 4 to 6 or The ratio is 2 to 3.

Every ratio can be written in 3 ways: Order matters in a ratio. What are some other ways we can write the ratio of basketball to footballs? Every ratio can be written in 3 ways: 4 to 6 4 : 6 4 6 First quantity to Second quantity Careful!! Order matters in a ratio. 4 to 6 Is NOT the same as 6 to 4 First quantity : Second quantity First quantity divided by the second quantity (as a fraction).

Simplifying Ratios In the Football & Basketball example, we changed 4:6 to 2:3 This is called Simplifying a ratio We did it by dividing each number by 2 2 was the highest common factor

Try to simplify these 4:1 6:1 1:2 1:5 5:2 !! 8:2 18:3 4:8 5:25 5:2

Sharing an amount in a given ratio “Bart and Maggie share a bag of 16 sweets in the ratio 3:1” This means “for every 3 sweets Bart gets, Maggie gets 1” 4 12

16 ÷ 4 = 4 in a share 1 x 4 1 share 4 3 x 4 3 shares 12 “Bart and Maggie share a bag of 16 sweets in the ratio 3:1” … quicker way…. Another way to think of this 3:1 is shares Bart gets 3 shares to Maggie’s 1 So there are actually 4 shares 16 sweets shared by 4 16 ÷ 4 = 4 in a share 1 x 4 1 share 4 3 x 4 3 shares 12

Write the ratio of sandwiches to coke bottles 3 different ways. 6:8 , 6 to 8, and 6 8 Since a fraction can be simplified, We can simplify the ratio 6/8 to 3/4. The ratio of sandwiches to coke bottles can also be expressed as 3 : 4 or 3 to 4. In other words, ratios can be simplified to form equivalent ratios.

Equivalent Ratios Simplify the following ratios: 4 to 8 10 to 8 8 8 / 4 2 HCF = 4 Step 1 – Write the ratio as a fraction Step 2 – Simplify the fraction (Find the highest common factor (HCF) of both numbers and divide the numerator and denominator by the HCF). Step 3 – Write the equivalent ratio in the same form as the question

The ratio 2 : 3 can be expressed as Equivalent Ratios can be formed by multiplying the ratio by any number. For example, the ratio 2 : 3 can also be written as 4 : 6 (multiply original ratio by 2) 6 : 9 (multiply original ratio by 3) 8 : 12 (multiply original ratio by 4) The ratio 2 : 3 can be expressed as 2x to 3x (multiply the original ratio by any number x)