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Fractions, Decimals & Percentages

META
MathematicsMathematical Thinking|Ages 9—10|ID: mt_hlGKg5M7qJ

Look for and use mathematical structure: exploit the relationship between fractions, decimals, and percentages; use factor pairs to simplify multiplication; apply angle facts to find unknowns; use properties of regular polygons systematically

Mastery Evidence

  • Use the structure 25 × 16 = 25 × 4 × 4 = 100 × 4 = 400 by exploiting factor pairs
  • Recognise that 0.75 = 3/4 = 75% and use whichever form is most efficient for the problem
  • Use the fact that angles on a straight line sum to 180° as a structural tool to find missing angles

Assessment Prompt

“When [child] notices that fractions, decimals, and percentages are just different ways of writing the same thing, do they use that understanding to switch between them fluidly when it makes a calculation easier?”

Prerequisites4

Show full prerequisite tree
  • Factors, multiples, and primes soft

    Factor pairs as structural tool for simplifying multiplication

  • Using Mathematical Structure hard

    Age 8-9 using structure is prerequisite to age 9-10 level

    • Shape patterns (age 7+) hard

      Age 7-8 using structure is prerequisite to age 8-9 level

      • The three digits of a three-digit number soft

        Three-digit place-value patterns exercise using structure

        • A Hundred Is Ten Tens hard

          Three-digit place value requires understanding 100 as a unit

          • A Ten Is Ten Ones hard

            100 as ten tens extends understanding of 10 as ten ones

            • The teen numbers hard

              Understanding 10 as a bundle builds on understanding teen numbers as 'a ten and some ones'

              • How Many in Total? hard

                Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

                • One-to-one counting hard

                  Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Reading and writing numbers to 20 hard

                Composing/decomposing teen numbers requires reading and writing those numerals

                • How Many in Total? hard

                  Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

                  • One-to-one counting hard

                    Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

                • Writing digits 0-9 hard

                  Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

          • The two digits of a two-digit number hard

            Must understand two-digit place value before extending to hundreds

            • A Ten Is Ten Ones hard

              Understanding tens and ones place value requires the concept of 10 as a bundle

              • The teen numbers hard

                Understanding 10 as a bundle builds on understanding teen numbers as 'a ten and some ones'

                • How Many in Total? hard

                  Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

                  • One-to-one counting hard

                    Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

                • Reading and writing numbers to 20 hard

                  Composing/decomposing teen numbers requires reading and writing those numerals

                  • How Many in Total? hard

                    Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

                    • One-to-one counting hard

                      Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

                  • Writing digits 0-9 hard

                    Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

            • The teen numbers hard

              General two-digit place value extends from understanding teen number composition

              • How Many in Total? hard

                Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

                • One-to-one counting hard

                  Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Reading and writing numbers to 20 hard

                Composing/decomposing teen numbers requires reading and writing those numerals

                • How Many in Total? hard

                  Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

                  • One-to-one counting hard

                    Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

                • Writing digits 0-9 hard

                  Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

        • The two digits of a two-digit number hard

          Three-digit PV extends two-digit PV (tens and ones)

          • A Ten Is Ten Ones hard

            Understanding tens and ones place value requires the concept of 10 as a bundle

            • The teen numbers hard

              Understanding 10 as a bundle builds on understanding teen numbers as 'a ten and some ones'

              • How Many in Total? hard

                Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

                • One-to-one counting hard

                  Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Reading and writing numbers to 20 hard

                Composing/decomposing teen numbers requires reading and writing those numerals

                • How Many in Total? hard

                  Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

                  • One-to-one counting hard

                    Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

                • Writing digits 0-9 hard

                  Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

          • The teen numbers hard

            General two-digit place value extends from understanding teen number composition

            • How Many in Total? hard

              Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

              • One-to-one counting hard

                Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

            • Reading and writing numbers to 20 hard

              Composing/decomposing teen numbers requires reading and writing those numerals

              • How Many in Total? hard

                Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

                • One-to-one counting hard

                  Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Writing digits 0-9 hard

                Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

      • Shape patterns hard

        Age 7-8 using structure builds on age 6-7

        • Addition in any order soft

          Deliberately applying commutativity to make addition easier exercises using structure

        • The two digits of a two-digit number soft

          Using place-value structure (tens and ones) to solve problems efficiently

          • A Ten Is Ten Ones hard

            Understanding tens and ones place value requires the concept of 10 as a bundle

            • The teen numbers hard

              Understanding 10 as a bundle builds on understanding teen numbers as 'a ten and some ones'

              • How Many in Total? hard

                Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

                • One-to-one counting hard

                  Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Reading and writing numbers to 20 hard

                Composing/decomposing teen numbers requires reading and writing those numerals

                • How Many in Total? hard

                  Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

                  • One-to-one counting hard

                    Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

                • Writing digits 0-9 hard

                  Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

          • The teen numbers hard

            General two-digit place value extends from understanding teen number composition

            • How Many in Total? hard

              Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

              • One-to-one counting hard

                Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

            • Reading and writing numbers to 20 hard

              Composing/decomposing teen numbers requires reading and writing those numerals

              • How Many in Total? hard

                Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

                • One-to-one counting hard

                  Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Writing digits 0-9 hard

                Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

        • Spotting mathematical patterns hard

          Age 6-7 using structure deliberately builds on age 5-6 noticing simple patterns and structure

          • Addition as combining or putting together two soft

            Noticing commutativity of addition exercises spotting structural patterns

            • How Many in Total? hard

              Understanding addition as combining groups requires knowing numbers represent quantities (cardinality)

              • One-to-one counting hard

                Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

          • The teen numbers soft

            Recognising teen numbers as 'ten and some more' exercises noticing structure

            • How Many in Total? hard

              Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

              • One-to-one counting hard

                Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

            • Reading and writing numbers to 20 hard

              Composing/decomposing teen numbers requires reading and writing those numerals

              • How Many in Total? hard

                Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

                • One-to-one counting hard

                  Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Writing digits 0-9 hard

                Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

      • Parallel and perpendicular lines soft

        Classifying lines by properties exercises structural thinking

        • Right Angles & Turns hard

          Perpendicular lines require understanding right angles

          • Understanding angles hard

            Identifying right angles requires understanding what an angle is

            • 2-D shapes (age 6+) soft

              Understanding angles as shape properties requires knowing basic shape properties

              • Angles in triangles (age 6+) soft

                Understanding defining attributes supports describing shape properties formally

                • 2-D shapes hard

                  Distinguishing defining vs non-defining attributes requires knowing common 2-D shape names first

                • 3-D shapes (age 5+) hard

                  Identifying defining attributes builds on informal analysis and comparison of shapes

                  • 2-D shapes hard

                    Analysing and comparing shapes requires being able to name them first

                  • 3-D shapes hard

                    Analysing 3-D shapes requires recognising and naming them

              • 2-D shapes hard

                Describing properties of 2-D shapes (sides, symmetry) requires knowing the shapes first

              • 3-D shapes (age 5+) hard

                Formal property description extends informal analysis of sides and vertices

                • 2-D shapes hard

                  Analysing and comparing shapes requires being able to name them first

                • 3-D shapes hard

                  Analysing 3-D shapes requires recognising and naming them

            • Position, direction, and movement hard

              Recognising angles as turns extends Y2 work on quarter/half/three-quarter turns

              • Positional Language hard

                Position/direction vocabulary with right angles extends basic positional language

              • Turns & Directions hard

                Right-angle turns (clockwise/anti-clockwise) build directly on whole/half/quarter turns from Year 1

          • Types of angles (age 8+) soft

            Identifying right angles and turns is supported by the convention of marking right angles with a small square

          • Position, direction, and movement hard

            Right angles as quarter turns extends Y2 turn vocabulary

            • Positional Language hard

              Position/direction vocabulary with right angles extends basic positional language

            • Turns & Directions hard

              Right-angle turns (clockwise/anti-clockwise) build directly on whole/half/quarter turns from Year 1

              • What Is a Half? soft

                Understanding half and quarter turns benefits from the concept of halves and quarters

                • Division as equal sharing hard

                  Finding a half requires equal sharing into 2 groups — a division concept

                  • Subtraction as taking away or separating hard

                    Division as equal sharing/grouping requires understanding subtraction as taking away/separating

                    • How Many in Total? hard

                      Understanding subtraction as taking away requires knowing numbers represent quantities (cardinality)

                      • One-to-one counting hard

                        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Positional Language hard

                Describing movement and turns builds on positional language

        • Positional Language soft

          Horizontal/vertical builds on positional vocabulary

      • Spotting Patterns soft

        Noticing place-value and operational structures in maths is the domain-specific application of the universal pattern-recognition habit

        • Connecting New & Old Ideas soft

          Spotting patterns across domains is an extension of the habit of connecting new ideas to existing ones

          • Thinking Before Starting hard

            Making connections between new and old ideas requires the habit of activating prior knowledge first

            • Persisting When It's Hard hard

              Activating prior knowledge requires the foundational habit of persistent engagement with new material

    • Dividing by 10 and 100 soft

      Dividing by 10/100 exercises place-value structural patterns

      • Tenths (age 8+) hard

        Must understand hundredths to identify digit values when dividing by 10/100

        • Tenths hard

          Count in tenths is prerequisite to extending to hundredths

          • Fractions of amounts hard

            Tenths extend fraction understanding from halves, thirds, quarters

            • Finding halves and quarters (age 5+) hard

              Working with 1/4, 2/4, 3/4 extends from Y1 understanding of quarters

              • What Is a Half? hard

                Understanding quarters extends from understanding halves — both are equal parts but quarters requires dividing into 4

                • Division as equal sharing hard

                  Finding a half requires equal sharing into 2 groups — a division concept

                  • Subtraction as taking away or separating hard

                    Division as equal sharing/grouping requires understanding subtraction as taking away/separating

                    • How Many in Total? hard

                      Understanding subtraction as taking away requires knowing numbers represent quantities (cardinality)

                      • One-to-one counting hard

                        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

            • What Is a Half? hard

              Working with fractions extends from Y1 understanding of halves

              • Division as equal sharing hard

                Finding a half requires equal sharing into 2 groups — a division concept

                • Subtraction as taking away or separating hard

                  Division as equal sharing/grouping requires understanding subtraction as taking away/separating

                  • How Many in Total? hard

                    Understanding subtraction as taking away requires knowing numbers represent quantities (cardinality)

                    • One-to-one counting hard

                      Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

            • Division as equal sharing soft

              Finding fractions of quantities uses equal sharing (division)

              • Subtraction as taking away or separating hard

                Division as equal sharing/grouping requires understanding subtraction as taking away/separating

                • How Many in Total? hard

                  Understanding subtraction as taking away requires knowing numbers represent quantities (cardinality)

                  • One-to-one counting hard

                    Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

            • Fraction Notation hard

              Writing fractions like 1/3 and 3/4 requires knowing numerator and denominator

          • Counting in 2s soft

            Skip counting supports counting in tenths

      • Decimal equivalents of tenths and hundredths hard

        Must know decimal notation to express results of dividing by 10/100

        • Tenths (age 8+) hard

          Must understand hundredths before writing decimal equivalents

          • Tenths hard

            Count in tenths is prerequisite to extending to hundredths

        • Decimal & Percent Notation hard

          Writing decimal equivalents of tenths and hundredths requires decimal point and place-value vocabulary

    • Spotting Patterns soft

      Using mathematical structure (distributive property, fraction equivalence) draws on the universal pattern-and-structure habit

      • Connecting New & Old Ideas soft

        Spotting patterns across domains is an extension of the habit of connecting new ideas to existing ones

        • Thinking Before Starting hard

          Making connections between new and old ideas requires the habit of activating prior knowledge first

          • Persisting When It's Hard hard

            Activating prior knowledge requires the foundational habit of persistent engagement with new material

    • Understanding angles (age 8+) soft

      Quadrilateral classification exercises using structure (shape hierarchy)

      • 2-D shapes (age 6+) hard

        Identifying 2D shape properties is prerequisite to classifying by shared attributes

        • Angles in triangles (age 6+) soft

          Understanding defining attributes supports describing shape properties formally

          • 2-D shapes hard

            Distinguishing defining vs non-defining attributes requires knowing common 2-D shape names first

          • 3-D shapes (age 5+) hard

            Identifying defining attributes builds on informal analysis and comparison of shapes

            • 2-D shapes hard

              Analysing and comparing shapes requires being able to name them first

            • 3-D shapes hard

              Analysing 3-D shapes requires recognising and naming them

        • 2-D shapes hard

          Describing properties of 2-D shapes (sides, symmetry) requires knowing the shapes first

        • 3-D shapes (age 5+) hard

          Formal property description extends informal analysis of sides and vertices

          • 2-D shapes hard

            Analysing and comparing shapes requires being able to name them first

          • 3-D shapes hard

            Analysing 3-D shapes requires recognising and naming them

      • Angles in triangles (age 7+) hard

        Recognising shapes by attributes is prerequisite to quadrilateral hierarchy classification

        • Angles in triangles (age 6+) hard

          Drawing shapes by attributes extends understanding defining vs non-defining attributes

          • 2-D shapes hard

            Distinguishing defining vs non-defining attributes requires knowing common 2-D shape names first

          • 3-D shapes (age 5+) hard

            Identifying defining attributes builds on informal analysis and comparison of shapes

            • 2-D shapes hard

              Analysing and comparing shapes requires being able to name them first

            • 3-D shapes hard

              Analysing 3-D shapes requires recognising and naming them

        • 2-D shapes (age 6+) hard

          Identifying pentagons, hexagons, quadrilaterals extends knowing 2-D shape properties

          • Angles in triangles (age 6+) soft

            Understanding defining attributes supports describing shape properties formally

            • 2-D shapes hard

              Distinguishing defining vs non-defining attributes requires knowing common 2-D shape names first

            • 3-D shapes (age 5+) hard

              Identifying defining attributes builds on informal analysis and comparison of shapes

              • 2-D shapes hard

                Analysing and comparing shapes requires being able to name them first

              • 3-D shapes hard

                Analysing 3-D shapes requires recognising and naming them

          • 2-D shapes hard

            Describing properties of 2-D shapes (sides, symmetry) requires knowing the shapes first

          • 3-D shapes (age 5+) hard

            Formal property description extends informal analysis of sides and vertices

            • 2-D shapes hard

              Analysing and comparing shapes requires being able to name them first

            • 3-D shapes hard

              Analysing 3-D shapes requires recognising and naming them

  • Angle Sum Rules soft

    Angle facts (360°, 180°) are structural tools for finding unknowns

    • Types of angles (age 8+) hard

      Angle sum rules (360° at a point, 180° on a line) are applied through reading angle diagrams with correct notation

    • Degrees and turns hard

      Angle facts (at a point = 360°) require degree system knowledge

      • What Is an Angle? hard

        Degree measurement system requires understanding what an angle is

        • Types of angles hard

          Angle definition builds on understanding right angles

          • Right Angles & Turns hard

            Identifying right angles and greater/less than right angle is prerequisite to naming acute/obtuse

            • Understanding angles hard

              Identifying right angles requires understanding what an angle is

              • 2-D shapes (age 6+) soft

                Understanding angles as shape properties requires knowing basic shape properties

                • Angles in triangles (age 6+) soft

                  Understanding defining attributes supports describing shape properties formally

                  • 2-D shapes hard

                    Distinguishing defining vs non-defining attributes requires knowing common 2-D shape names first

                  • 3-D shapes (age 5+) hard

                    Identifying defining attributes builds on informal analysis and comparison of shapes

                    • 2-D shapes hard

                      Analysing and comparing shapes requires being able to name them first

                    • 3-D shapes hard

                      Analysing 3-D shapes requires recognising and naming them

                • 2-D shapes hard

                  Describing properties of 2-D shapes (sides, symmetry) requires knowing the shapes first

                • 3-D shapes (age 5+) hard

                  Formal property description extends informal analysis of sides and vertices

                  • 2-D shapes hard

                    Analysing and comparing shapes requires being able to name them first

                  • 3-D shapes hard

                    Analysing 3-D shapes requires recognising and naming them

              • Position, direction, and movement hard

                Recognising angles as turns extends Y2 work on quarter/half/three-quarter turns

            • Types of angles (age 8+) soft

              Identifying right angles and turns is supported by the convention of marking right angles with a small square

            • Position, direction, and movement hard

              Right angles as quarter turns extends Y2 turn vocabulary

              • Positional Language hard

                Position/direction vocabulary with right angles extends basic positional language

              • Turns & Directions hard

                Right-angle turns (clockwise/anti-clockwise) build directly on whole/half/quarter turns from Year 1

        • Right Angles & Turns hard

          Angle definition builds on classifying acute/obtuse angles

          • Understanding angles hard

            Identifying right angles requires understanding what an angle is

            • 2-D shapes (age 6+) soft

              Understanding angles as shape properties requires knowing basic shape properties

              • Angles in triangles (age 6+) soft

                Understanding defining attributes supports describing shape properties formally

                • 2-D shapes hard

                  Distinguishing defining vs non-defining attributes requires knowing common 2-D shape names first

                • 3-D shapes (age 5+) hard

                  Identifying defining attributes builds on informal analysis and comparison of shapes

                  • 2-D shapes hard

                    Analysing and comparing shapes requires being able to name them first

                  • 3-D shapes hard

                    Analysing 3-D shapes requires recognising and naming them

              • 2-D shapes hard

                Describing properties of 2-D shapes (sides, symmetry) requires knowing the shapes first

              • 3-D shapes (age 5+) hard

                Formal property description extends informal analysis of sides and vertices

                • 2-D shapes hard

                  Analysing and comparing shapes requires being able to name them first

                • 3-D shapes hard

                  Analysing 3-D shapes requires recognising and naming them

            • Position, direction, and movement hard

              Recognising angles as turns extends Y2 work on quarter/half/three-quarter turns

              • Positional Language hard

                Position/direction vocabulary with right angles extends basic positional language

              • Turns & Directions hard

                Right-angle turns (clockwise/anti-clockwise) build directly on whole/half/quarter turns from Year 1

          • Types of angles (age 8+) soft

            Identifying right angles and turns is supported by the convention of marking right angles with a small square

          • Position, direction, and movement hard

            Right angles as quarter turns extends Y2 turn vocabulary

            • Positional Language hard

              Position/direction vocabulary with right angles extends basic positional language

            • Turns & Directions hard

              Right-angle turns (clockwise/anti-clockwise) build directly on whole/half/quarter turns from Year 1

              • What Is a Half? soft

                Understanding half and quarter turns benefits from the concept of halves and quarters

                • Division as equal sharing hard

                  Finding a half requires equal sharing into 2 groups — a division concept

                  • Subtraction as taking away or separating hard

                    Division as equal sharing/grouping requires understanding subtraction as taking away/separating

                    • How Many in Total? hard

                      Understanding subtraction as taking away requires knowing numbers represent quantities (cardinality)

                      • One-to-one counting hard

                        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

              • Positional Language hard

                Describing movement and turns builds on positional language

  • Spotting Patterns soft

    Exploiting relationships between fractions, decimals and percentages requires pattern recognition across representations

    • Connecting New & Old Ideas soft

      Spotting patterns across domains is an extension of the habit of connecting new ideas to existing ones

      • Thinking Before Starting hard

        Making connections between new and old ideas requires the habit of activating prior knowledge first

        • Persisting When It's Hard hard

          Activating prior knowledge requires the foundational habit of persistent engagement with new material

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