Math is Fun: Solving One-Step Equations Using Addition and Subtraction

Balance Challenge

Display a simple balance scale image.

Ask:

• What happens if you add 5 pounds to only one side?
• What must happen to keep the scale balanced?

Next, write:

x + 3 = 7

Ask students:

• What number might x be?
• How could we find out?

The Balance Principle

Introduce the concept:

Whatever you do to one side of an equation, you must do to the other side.

Demonstrate:

x + 5 = 12

Subtract 5 from both sides:

x + 5 − 5 = 12 − 5

x = 7

Introduce vocabulary:

• Equation
• Variable
• Balance
• Inverse Operation
• Solution

Discuss how addition and subtraction are inverse operations.

Partner Prediction Activity

Students work in pairs at one computer.

One student is the Navigator, and one is the Recorder.

Using the Math Is Fun Balance activity, the Navigator predicts what will happen before selecting a button.

Examples:

• "If we subtract 2 from both sides, what will happen?"
• "Will the equation still be balanced?"
• "Will we be closer to solving for x?"

The Recorder documents predictions and results.

After three equations, students switch roles.

Equation Detective Pairs

Students continue working with a partner.

Each pair generates three new equations using the website's "New Equation" button.

For each equation:

1. Student A suggests the next move.
2. Student B explains why it should work.
3. Both agree before making the move.
4. Students record each step.

Think-Aloud Requirement

Partners must explain:

• Why did they select a particular operation?
• How is the balance maintained?
• Whether there might be another solution strategy.

Collaborative Challenge

Pairs compete to solve an equation using the fewest possible moves while maintaining accuracy.

Exit Ticket

Solve:

x + 8 = 15

Solve:

x - 6 = 4

Answer:

1. Why must both sides remain balanced?
2. What is an inverse operation?
3. How can you check your answer?

Success Criteria

Students can:

✓ Solve one-step equations.

✓ Explain the balance principle.

✓ Use inverse operations correctly.

✓ Verify solutions.

Create-and-Swap Activity

Working in pairs, students create two real-world situations that can be represented by one-step equations.

Examples:

• Money spent and remaining
• Weight added to a package
• Distance traveled

Students write:

• A word problem
• The equation
• The solution

Pairs exchange problems with another pair and solve them together.

Gallery Walk

Pairs display their problems around the room.

Students visit other groups' problems and discuss different solution methods.