Whiteboard · Page 1 / 10
Fraction evidenceLive observation

Remove the second fractional amount from the first.

Problem3/4 − 1/6
Common form9/12 − 2/12
Exact result7/12
Decimal check0.583
Fraction Subtraction SimulationPaused
Mode

What does subtracting fractions mean?

Take one fractional amount away from another and measure what remains. Pieces must have the same size before their counts can be subtracted.

  1. Model both fractions.
  2. Create equal-sized pieces.
  3. Remove, then simplify.

Fraction workbench

Current calculation

Least common denominator12
Converted first9/12
Converted second2/12
Simplified result7/12

View and piece focus

Drag to pan, zoom with the wheel or buttons, and tap a piece for a short explanation.

Value comparison

Teacher demonstrations

Guided visual lecture

Chapter 1 of 80%

Ready. The first visual beat defines fraction subtraction before the method begins.

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

1. Meaning of fraction subtraction

Watch: A full visual definition appears before any calculation.

Chapters

Fraction subtraction formulas

Same denominator: a/c − b/c = (a − b)/c

Unlike denominators: a/b − c/d = (ad − bc)/bd

Using the least common denominator: convert both fractions to equivalent fractions with denominator LCM(b, d), then subtract their numerators.

Simplify: divide numerator and denominator by their greatest common factor.

Learning objectives

  • Explain subtraction as removing one fractional amount.
  • Recognize why pieces need equal size.
  • Find a least common denominator.
  • Subtract and simplify exactly.

Suggested investigations

  • Compare 5/8 − 2/8 with unlike denominators.
  • Create a result that simplifies by a factor of two.
  • Make the second fraction larger and inspect the negative result.
  • Confirm the result by adding the removed fraction back.

Questions for exploration

  • Why do denominators stay fixed after conversion?
  • Why does multiplying numerator and denominator preserve value?
  • How does the number line show a negative result?

Teacher whiteboard

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

Knowledge check

Seven questions0 / 7

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