Understanding Proportions in Everyday Life
Grade 7 Mathematics Discovering ratios and proportions around us
What Do These Have in Common?
A recipe that serves 4 people A map showing 1 inch = 10 miles A photo enlarged from 4×6 to 8×12 inches
What is a Proportion?
A proportion is two ratios that are equal Example: 2:4 = 3:6 Both ratios show the same relationship We can write it as 2/4 = 3/6
Cross-Multiplication Check
Step 1: Write the proportion as fractions Step 2: Multiply diagonally (cross-multiply) Step 3: If products are equal, it's a proportion! Try it: Does 3/4 = 6/8?
Proportions vs. Non-Proportions
{"left":"PROPORTIONS:\n2:3 = 4:6\n1:5 = 3:15","right":"NON-PROPORTIONS:\n2:3 ≠ 4:7\n1:4 ≠ 2:9"}
Real-World Proportions
Cooking: 2 cups flour for 1 cake = 4 cups flour for 2 cakes Sports: 3 goals in 2 games = 6 goals in 4 games Art: Golden ratio in paintings and architecture Shopping: Buy 2 get 1 free deals
Create Your Own Proportion
Think of something from your life Create two equivalent ratios Use cross-multiplication to check Share with a partner
Key Takeaway
"Proportions help us understand how quantities relate to each other in our everyday world."