AC9M4N03 • Year 4 Maths

AC9M4N03: Equivalent fractions and decimals

Find equivalent representations of fractions using related denominators and make connections between fractions and decimal notation.

What students learn in AC9M4N03

Equivalent fractions name the same point or amount even though they use different-sized parts. Multiplying or dividing the numerator and denominator by the same factor preserves value.

Learning routine: Identify equal whole → Scale numerator and denominator → Verify model → Connect to tenths/hundredths → Compare

Success looks like

  • Generate equivalent fractions
  • Use related denominators
  • Connect tenths/hundredths
  • Convert common fractions to decimals
  • Compare representations
Key vocabulary
equivalent fractions
fractions representing the same quantity
numerator
the number of selected equal parts
denominator
the number of equal parts in one whole
Concept models and worked thinking

Show 1/2 = 2/4 = 5/10 = 50/100

1/2
=
2/4
=
5/10
=
50/100

Each model covers the same proportion of an equal-sized whole. The number of parts changes, but the shaded amount does not.

  1. Use equal-sized wholes. One coloured half has the same area as two coloured quarters.
  2. Split each part into smaller equal parts: 1/2 = 2/4 = 5/10 = 50/100.
  3. Read 5/10 as 0.5 and 50/100 as 0.50. Both decimals name the same number.

Connect fractions with decimal notation

FractionHundredthsDecimal1/250/1000.501/425/1000.253/475/1000.753/1030/1000.30

Fractions with denominators 10 or 100 connect directly to decimal place value. For the common fractions in this table, the denominators can be multiplied to make 10 or 100. Do not assume every fraction can be written exactly using only tenths or hundredths.

Worked example: 3/5 = 6/10 = 60/100 = 0.6 = 0.60. Splitting fifths into tenths doubles both counts; splitting tenths into hundredths multiplies both counts by 10. The value stays the same.

Quick check: Is 0.04 the same as 4/10? No: 0.04 is four hundredths. Four tenths are 0.4 or 0.40.

Find a missing numerator, then reverse the process

Example: 2/3 = ?/12. Each third is divided into four smaller parts. Multiply both numbers by 4: 2/3 = 8/12. In reverse, grouping 8 selected twelfths and all 12 twelfths in fours gives 2/3.

Teacher asks: Why must both numbers change by the same factor? Student explains: The number of selected parts and the total number of parts change together; the same amount of the same whole is represented.

Equivalent fractions share a number-line position

Same number, different equal intervalsA01B01

The blue point is 2/4 on the upper line and 3/6 on the lower line. Both points are halfway from 0 to 1, so 2/4 = 3/6 = 1/2.

Curriculum coverage and elaborations

Content description: find equivalent representations of fractions using related denominators and make connections between fractions and decimal notation.

The following teaching examples cover the curriculum elaborations.

E1: Fraction families in collections

Arrange 20 counters in four equal rows of five. Colour three rows. Fifteen of twenty counters are coloured, and three of four equal rows are coloured: 15/20 = 3/4. Regroup the same collection into ten pairs and identify 2/5 = 4/10 in a separate selection of eight counters.

Look for: The whole collection stays fixed while students change the equal groups. Ask students to show the selected counters, rather than only recite a rule.

E2: Capacity subdivisions

Use the same cup as one whole. Half a cup can be measured as two quarter-cups or four eighth-cups: 1/2 = 2/4 = 4/8. Use water or dry counters to model the amounts without needing to read a curved water surface.

Check: How many eighth-cup measures match three quarter-cups? Six, because each quarter contains two eighths.

E3: Paper folding and decimal names

Fold equal paper rectangles into halves, quarters and eighths. Unfold and shade the same half: 1/2 = 2/4 = 4/8. For a second model, mark a strip into five equal parts, colour two parts, then halve every fifth. Record 2/5 = 4/10 = 0.4.

Check: The outside size and coloured region must remain unchanged; every part within one partition must be equal.

E4: Fractions of a metre

One metre is 100 centimetres. Divide a metre strip into four equal lengths: 100 ÷ 4 = 25, so 1/4 m = 25/100 m = 0.25 m = 25 cm. One tenth of a metre is 10 cm, so 1/10 m = 0.10 m = 10 cm.

Check: Three fifths of a metre are 60 cm or 0.60 m because one fifth is 20 cm.

E5: Arrays connect fractions and operations

One collection of equal counters

The array shows 3 × 4 = 12. One of three equal rows contains 4 counters: 12 ÷ 3 = 4 and 1/3 of 12 is 4. One of the four columns contains 3 counters: 12 ÷ 4 = 3 and 1/4 of 12 is 3.

Teacher asks: Why can one third and one quarter of the same collection be different counts? Expected answer: Three equal groups are larger than four equal groups when the total collection is unchanged.

Guided learning activities

1. Fraction wall reasoning

Build a fraction wall and identify aligned endpoints for halves, quarters, fifths, tenths and hundredths.

1/2
2/4
3/5
6/10

2. Scale both parts

Start from 2/5 each time and multiply both numerator and denominator by the same number.

  • Using ×2: 2/5 = 4/10.
  • Using ×5: 2/5 = 10/25.
  • Using ×10: 2/5 = 20/50.
  • Using ×20: 2/5 = 40/100 = 0.40.

These are separate equivalent representations of 2/5; each calculation starts from the original fraction.

3. Fraction–decimal match

Match common fractions to decimal representations and justify using hundredths.

1/4 ↔ 0.253/5 ↔ 0.607/10 ↔ 0.709/20 ↔ 0.45
Revision Notes

Core idea: Equivalent fractions name the same point or amount even though they use different-sized parts. Multiplying or dividing the numerator and denominator by the same factor preserves value.

Remember

  • Generate equivalent fractions
  • Use related denominators
  • Connect tenths/hundredths
  • Convert common fractions to decimals
  • Compare representations

Important questions

  • Give two equivalents for 3/5. 6/10 and 60/100. Multiply both parts of 3/5 by 2 or by 20.
  • Write 1/4 as hundredths and a decimal. 1/4 = 25/100 = 0.25 because both fraction parts are multiplied by 25.
  • Is 6/10 equivalent to 3/5? Prove it. Yes. Each fifth contains two tenths, so 3 fifths contain 6 tenths. Dividing 6 and 10 by 2 also gives 3/5.
  • Which is greater: 2/5 or 0.45? 0.45 is greater. Rename 2/5 as 40/100 = 0.40, then compare 40 hundredths with 45 hundredths.
  • Explain why 4/8 = 1/2. Four of eight equal parts cover half of the same whole. Divide numerator and denominator by 4 to get 1/2.
Support, core and extension

Before this lesson: Students recognise equal parts, unit fractions and multiplication/division facts. Support: Use two identical strips and match halves with quarters before using number sentences. Core: Connect a model, related-denominator fraction and decimal for halves, quarters, fifths, tenths and hundredths. Extend within this code: Explain a missing numerator or denominator and justify a fraction such as 9/20 = 45/100 = 0.45.

Boundary: Use models and related denominators. General fraction algorithms, recurring decimals and formal fraction arithmetic are not the target here.

Assessment-style questions and review hints
  1. Complete 3/4 = ?/20 and explain. Review hint: Find the multiplier from 4 to 20. Answer: 15/20; multiply both parts by 5.
  2. A bottle contains 2/5 litre. Write the amount in tenths and as a decimal. Review hint: Split every fifth into two tenths. Answer: 4/10 L = 0.4 L.
  3. Draw a collection to show 1/3 = 4/12. Review hint: Use three equal groups. Evidence: Twelve counters in three groups of four, with one group coloured.
How to use this unit

Use the Topic Guide, then project the Classroom View. Complete the written worksheet tasks before Practice and Test. Drawing tasks need an adult to inspect the actual work; a completion tick alone does not establish mastery.

Quick check and feedback
  1. Write two fractions equivalent to 3/5. 6/10 and 60/100 are correct because numerator and denominator are scaled by the same factor.
  2. Write 7/10 as hundredths and as a decimal. 70/100 and 0.70.
  3. Which is larger, 2/5 or 0.45? 0.45 is larger because 2/5 = 4/10 = 40/100 = 0.40.

Mastery evidence: Students keep the whole constant and can prove equivalence with a model, a related denominator or decimal place value.

AC9M4N03 Teacher Slides

Project the Classroom View and open one teaching section at a time.

Open Classroom View
Common misconceptions
  • Only numerator changed — Multiply or divide both numerator and denominator by the same non-zero factor.
  • Different-sized wholes compared — Equal-sized wholes are needed when using equal shaded amounts to demonstrate equivalence. The same fraction of different-sized wholes can be different amounts.
  • Denominator treated as decimal digits — 1/4 is 0.25, not 0.4.
  • Equivalent means identical notation — Equivalent representations look different but have the same value.
International curriculum mapping
AustraliaAustralian Curriculum v9.0AC9M4N03
VictoriaVictorian Curriculum F–10Year 4 Number: fractions and decimals.
NSWNSW CurriculumStage 2 Mathematics: fractions and decimals.
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Recommended: Intro to equivalent fractions | Fractions | 4th grade | Khan Academy

Khan Academy — See why different fraction names can represent the same amount.

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Curriculum equivalents: Victoria, NSW and international

Curriculum equivalents for Find equivalent representations of fractions using related denominators and make...

Mapped skill: find equivalent representations of fractions using related denominators and make connections between fractions and decimal notation

These references identify matching or closely related learning. Curriculum sequence, terminology and depth vary, so teachers should use the mapped skill and lesson difficulty to confirm suitability.

RegionCurriculum frameworkClosest level or code
AustraliaAustralian Curriculum v9.0AC9M4N03 · Year 4
VictoriaVictorian Curriculum F–10 Version 2.0 — MathematicsVC2M4N03 · Level 4
New South WalesNSW Mathematics K–10 Syllabus (2022)MA2-PF-01 · Stage 2
United States (USA)Common Core State Standards for MathematicsGrade 4
Canada (Ontario)Ontario Curriculum — MathematicsGrade 4
United Kingdom (England)National Curriculum in England — MathematicsYear 5, Key Stage 2
IndiaNCERT / CBSE — MathematicsClass 4

Australian Curriculum v9.0 is the canonical source for this SkillrHub lesson. Victoria and NSW entries name the closest published state codes or outcomes; international entries are planning references rather than claims of identical curricula.

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Official curriculum references
Related Year 4 Maths topics