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Understanding fractions (age 9+)

CONCEPTUAL
MathematicsFractions|Ages 9—10|ID: mt_09sySPqM9Z

Understand a fraction a/b with a > 1 as a sum of fractions 1/b (e.g. 3/5 = 1/5 + 1/5 + 1/5)

Mastery Evidence

  • Express 5/8 as a sum of five copies of 1/8
  • Show on a number line how 4/3 is built by iterating 1/3 four times
  • Explain why 7/4 = 1/4 + 1/4 + 1/4 + 1/4 + 1/4 + 1/4 + 1/4

Assessment Prompt

“If you ask [child] to show 4/5 as a sum of smaller equal fractions, can they write it out as 1/5 + 1/5 + 1/5 + 1/5?”

Prerequisites1

Show full prerequisite tree
  • Fractions of a whole hard

    Understanding a/b as a parts of size 1/b is prerequisite to understanding a/b as sum of 1/b

    • Fractions of amounts hard

      Recognising fractions of shapes/quantities is prerequisite to formal unit fraction understanding

      • 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

    • Fraction Notation hard

      Understanding a/b as a parts of 1/b requires numerator, denominator, and unit fraction vocabulary

    • Splitting shapes into equal parts (age 7+) hard

      Partition into equal shares is prerequisite to understanding unit fractions