MathIsimple
Lesson 5-3

Simple Equations

Introduction to equations and unknown quantities. Learn to solve simple addition and subtraction equations

Equal SignUnknown NumbersBalancingProblem Solving
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Key Concepts

Learn the fundamentals of equations and unknown quantities

Equal Sign Meaning

The equal sign (=) means 'is the same as' or 'balances'. Both sides of the equation must have the same value.

Examples:

3 + 2 = 5 (both sides equal 5)
7 - 3 = 4 (both sides equal 4)
6 = 2 + 4 (both sides equal 6)

Unknown Quantities

Sometimes we don't know a number in an equation. We use a question mark (?) or a box (□) to show the unknown.

Examples:

3 + ? = 7 (what number makes this true?)
□ - 2 = 5 (what number minus 2 equals 5?)
4 + ? = 9 (what number plus 4 equals 9?)

Balancing Equations

To keep an equation balanced, whatever you do to one side, you must do to the other side.

Examples:

If 3 + 2 = 5, then 3 + 2 + 1 = 5 + 1
If 7 - 3 = 4, then 7 - 3 - 1 = 4 - 1
Both sides must stay equal

Interactive Practice

Practice solving equations through interactive activities

Balance Scale Challenge

Use a virtual balance scale to solve equations.

Activity: Add or remove objects to balance both sides of the equation

Mystery Number Hunt

Find the missing number in simple equations.

Activity: Solve equations like 5 + ? = 8 and ? - 3 = 4

Equation Detective

Determine if equations are true or false.

Activity: Check if equations like 3 + 2 = 6 are correct

Example Library

See step-by-step solutions for different types of equations

Finding Unknown in Addition

Problem:

Solve: 5 + ? = 8

Solution:

? = 3

Steps:

  1. 1Start with the equation: 5 + ? = 8
  2. 2Think: what number plus 5 equals 8?
  3. 3Count: 5 + 1 = 6, 5 + 2 = 7, 5 + 3 = 8
  4. 4The missing number is 3

Visual:

5 + 3 = 8 (3 is the missing number)

Finding Unknown in Subtraction

Problem:

Solve: ? - 2 = 5

Solution:

? = 7

Steps:

  1. 1Start with the equation: ? - 2 = 5
  2. 2Think: what number minus 2 equals 5?
  3. 3Work backwards: 5 + 2 = 7
  4. 4Check: 7 - 2 = 5 ✓

Visual:

7 - 2 = 5 (7 is the missing number)

Balancing with Addition

Problem:

Keep balanced: 3 + 2 = 5

Solution:

Add 1 to both sides: 3 + 2 + 1 = 5 + 1

Steps:

  1. 1Start with: 3 + 2 = 5
  2. 2Add 1 to the left: 3 + 2 + 1 = 6
  3. 3Add 1 to the right: 5 + 1 = 6
  4. 4Both sides equal 6, so it's still balanced

Visual:

3 + 2 + 1 = 5 + 1 = 6 (both sides equal)

True or False Equations

Problem:

Is 4 + 3 = 6 true or false?

Solution:

False

Steps:

  1. 1Calculate the left side: 4 + 3 = 7
  2. 2Compare to right side: 6
  3. 37 ≠ 6 (7 is not equal to 6)
  4. 4This equation is false

Visual:

4 + 3 = 7, but the equation says 6, so it's false

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