Whiteboard · Page 1 / 10
Percentage evidenceLive observation

A percentage compares a part with a whole of one hundred.

ScenarioDiscount
Starting value$120.00
Percentage amount$24.00
Final result$96.00
Percentage MarketplacePaused
Mode

%What is a real-world percentage problem?

It connects a comparison out of 100 to an actual amount. Discounts, tax, tips, progress, and change all use the same whole–rate–part relationship.

  1. Identify the starting whole.
  2. Find the percentage part.
  3. Add or subtract for the situation.

Marketplace calculator

Current calculation

Whole$120.00
Rate as decimal0.20
Percentage part$24.00
Result$96.00

View and object focus

Drag to pan, zoom with the wheel or buttons, and tap a price, percent meter, or result for a short explanation.

Whole–part comparison

Teacher demonstrations

Guided visual lecture

Chapter 1 of 80%

Ready. The opening ten seconds define percentages visually before solving problems.

External recording: share this browser tab with tab audio enabled. Embedded audio is louder and recordable; no microphone is used.

1. Percent means out of one hundred

Watch: One hundred cells connect a percentage to a real amount.

Chapters

Percentage formulas

Percentage amount: part = whole × rate ÷ 100

Discount or decrease: final = whole − part

Tax, tip, markup, or increase: final = whole + part

Percent change: rate = (new − original) ÷ original × 100%

Learning objectives

  • Identify whole, rate, and percentage part.
  • Convert a percent to a decimal.
  • Model discounts, tax, tips, and change.
  • Estimate and check whether the direction is reasonable.

Suggested investigations

  • Compare a 20% discount with 20 dollars off.
  • Apply tax after a discount and observe the new whole.
  • Estimate 15% using 10% plus 5%.
  • Reverse a change using the original value.

Questions for exploration

  • Why does the same rate produce different parts for different wholes?
  • When does the final value increase or decrease?
  • Why is the original value used in percent change?

Teacher whiteboard

Use a finger, stylus, mouse, Android device, or smart board. Ten full-size pages keep their own drawings.

Knowledge check

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