🌟 Using Variables to Represent Unknown Quantities 🌟

Hi my clever Grade 6 algebra adventurers! 🌟

Today we’re learning how to use variables (letters like x, y, n) to stand for numbers we don’t know yet. This is the beginning of real algebra! Variables help us write rules and solve problems when we don’t know all the numbers. Let’s become variable experts together! 🔤

1. What is a Variable?

A variable is a letter that represents an unknown number.

Common letters: x, y, n, a

Example: “A number plus 8” can be written as x + 8

2. Writing Algebraic Expressions

“A number times 5” → 5x

“A number plus 9” → x + 9

“12 less than a number” → x - 12

“3 times a number minus 4” → 3x - 4

3. Evaluating Expressions (Plugging in Numbers)

Replace the variable with a number and calculate.

Example: Evaluate 4x + 7 when x = 6

4 × 6 + 7 = 24 + 7 = 31

4. Let’s Practice Together! 🎉

Question 1:

Write an expression: “A number multiplied by 6”

6x ⭐

Question 2:

Write: “9 more than a number”

x + 9 ⭐

Question 3:

Evaluate 5x - 3 when x = 8

5×8 - 3 = 40 - 3 = 37 ⭐

Question 4:

Evaluate 2y + 10 when y = 12

2×12 + 10 = 34 ⭐

Question 5 (Real Life):

You buy x pencils that cost $2 each and a notebook for $5. Write an expression for the total cost. Then find the total if x = 7.

Expression: 2x + 5
When x = 7: $19 ⭐

6. Real Life in Canada 🇨🇦

Buying hockey cards: 3x + 4 dollars
Monthly allowance: $20 + 5x (for extra chores)
Temperature: It was x degrees and dropped 8 degrees
Savings: You save $15 each week → 15w

You are a Variables Expert! 🏆

Wonderful work today! You now know how to use variables to represent unknown quantities.

This is the foundation of algebra and you’re doing great!

I’m so proud of you,

Keep using letters for unknown numbers in your daily life,
Mrs. Brenda ❤️

🔤🧠✨