Algebra

KS2

MA-Y6-D005

Using simple formulae expressed in words and symbols; generating and describing linear number sequences; expressing missing number problems algebraically; finding pairs of numbers that satisfy an equation with two unknowns; enumerating possibilities of combinations of two variables.

National Curriculum context

Algebra is introduced explicitly in Year 6 as a named domain, representing the formal beginning of symbolic mathematical reasoning that pupils will develop extensively throughout KS3 and beyond. Prior to Year 6, algebraic thinking has been present implicitly — in missing number problems from Year 1 onwards, in generalising pattern rules, and in the use of formulae for area and perimeter — but Year 6 formalises this into symbolic notation using letters to represent unknown or variable quantities. The transition from arithmetic to algebraic thinking is one of the most significant cognitive steps in mathematics education, and the Year 6 programme provides a carefully managed entry point through familiar contexts such as simple formulae and linear sequences. Work on equations with two unknowns introduces systematic enumeration of solutions, developing logical reasoning and laying groundwork for simultaneous equations at KS3. Teachers should emphasise the continuity between familiar arithmetic operations and their algebraic generalisations, helping pupils see algebra as a powerful tool for expressing and solving problems rather than a mysterious new subject.

3

Concepts

2

Clusters

0

Prerequisites

3

With difficulty levels

AI Direct: 3

Lesson Clusters

1

Use algebraic notation and formulae with letters for unknowns

introduction Curated

Algebraic notation and formulae is the gateway concept for Year 6 algebra, introducing the idea of using letters to represent unknowns. Must precede sequence and equation work.

1 concepts Patterns
2

Generate and describe linear sequences and solve equations in two variables

practice Curated

Linear sequences, two-variable equations and mathematical reasoning/justification are co-taught (C014 and C030 mutually co-teach). Together they represent the Year 6 algebra application and reasoning cluster.

2 concepts Patterns

Teaching Suggestions (1)

Study units and activities that deliver concepts in this domain.

Algebra

Mathematics Pattern Seeking
CPA Stage: concrete → pictorial → abstract NC Aim: reasoning
algebra tiles balance scales (physical or virtual) multilink cubes for sequences
algebra tiles function machines balance diagrams for equations sequence diagrams with term-to-term and position-to-term rules
Fluency targets: Use letters to represent unknowns and variables; Substitute values into simple formulae; Generate terms of a linear sequence given a rule; Find the nth term rule for simple linear sequences; Enumerate possibilities for equations with two unknowns

Concepts (3)

Algebraic Notation and Formulae

knowledge AI Direct

MA-Y6-C013

Mastery of algebraic notation means pupils can write, interpret and use simple algebraic expressions and formulae in which letters represent unknown or variable quantities, substituting values to evaluate expressions and constructing expressions from word descriptions. A fully secure pupil understands that a letter represents a number (which may be unknown, or may vary), that 3n means '3 times n', and that an expression like 2l + 2w is a general formula applicable to any rectangle — not just a specific case.

Teaching guidance

Draw explicitly on prior work with missing number problems to establish continuity: the box in □ + 5 = 12 is the same idea as n in n + 5 = 12. Introduce letter notation as a more efficient and general representation than boxes. Practise writing expressions from descriptions ('5 more than n' → n + 5; 'three times m, subtract 4' → 3m - 4). Substitution exercises — evaluating an expression for given values — should precede formula derivation. Connect to known formulae (area of rectangle: A = lw; perimeter of rectangle: P = 2(l + w)) as familiar examples. Avoid ambiguity: be clear about the difference between an expression (3n + 2) and an equation (3n + 2 = 17).

Vocabulary: algebra, expression, equation, formula, variable, unknown, substitute, evaluate, term, coefficient, letter symbol
Common misconceptions

Pupils often treat a letter in an expression as a label or abbreviation (e.g., a = apples) rather than as a number. Concatenation notation (3n meaning 3 × n) is unfamiliar and pupils may read it as 'thirty-n' or misinterpret it. Some pupils believe that different letters in an expression must represent different values (e.g., in a + b, a ≠ b). Pupils also confuse 'evaluate an expression' with 'solve an equation' — these are importantly different tasks.

Difficulty levels

Entry

Understanding that a letter represents an unknown number and evaluating simple expressions by substitution.

Example task

If n = 5, what is 3n + 2?

Model response: 3 × 5 + 2 = 15 + 2 = 17.

Developing

Writing algebraic expressions from word descriptions and evaluating expressions with two operations.

Example task

Write an expression for 'twice a number, subtract 7'. If the number is 12, evaluate.

Model response: 2n – 7. When n = 12: 2 × 12 – 7 = 24 – 7 = 17.

Expected

Using formulae in context, substituting values into multi-variable expressions, and forming expressions from problems.

Example task

The perimeter of a rectangle is P = 2(l + w). Find P when l = 8 and w = 5. A pizza costs £p. Write an expression for the cost of 3 pizzas and a £2 delivery charge.

Model response: P = 2(8 + 5) = 2 × 13 = 26. Pizza cost: 3p + 2.

CPA Stages

concrete

Using physical 'function machines' (boxes with input/output slots), mystery number envelopes, and concrete bar models where a letter card represents an unknown number of counters

Transition: Child writes algebraic expressions from word descriptions and solves simple equations by reasoning about the unknown

pictorial

Drawing bar models to represent algebraic expressions and equations, using substitution tables to evaluate expressions for different values

Transition: Child writes and evaluates algebraic expressions and solves one-step equations using bar models or inverse operations on paper

abstract

Writing, evaluating and solving algebraic expressions and simple equations mentally, using formulae in context, and explaining that a letter represents a number

Transition: Child uses algebraic notation fluently, evaluates expressions by substitution, and solves simple equations using inverse operations

Delivery rationale

Upper primary maths (Y6) — most pupils at pictorial/abstract stage. AI can deliver with virtual representations.

Linear Sequences and Two-Variable Equations

process AI Direct

MA-Y6-C014

Mastery means pupils can generate any term of a linear sequence given its first term and common difference, describe a sequence using the language of 'common difference' and 'term', and represent simple sequences and relationships using algebraic expressions. For two-variable equations, a fully secure pupil can enumerate all pairs of positive integers (or values within a given range) that satisfy an equation like a + b = 10 or 2x + y = 8 by working systematically.

Teaching guidance

Use real-world contexts for sequences: tile patterns, fence posts and panels, stair-step shapes. Ask pupils to describe the pattern in words before introducing algebraic notation. Progress from 'add n each time' descriptions to the nth term rule for linear sequences (though full nth term work is a KS3 objective). For two-variable equations, teach systematic enumeration: start with the smallest possible value for one variable, find the corresponding value for the other, and work through all possibilities in order, recording in a table. Connect to coordinate graph work by plotting solution pairs on a grid — visually, the solutions lie on a straight line.

Vocabulary: sequence, term, common difference, linear sequence, rule, two unknowns, equation, enumerate, systematically, solution, coordinate
Common misconceptions

Pupils confuse the term-to-term rule (add 4 each time) with the position-to-term rule (nth term = 4n - 1). When enumerating solutions to two-variable equations, pupils work unsystematically and miss solutions or count duplicates. Some pupils do not consider that variables can take the value 0. Explicit use of tables and a systematic left-to-right approach prevents most enumeration errors.

Difficulty levels

Entry

Continuing a linear sequence given the first few terms and describing the rule as 'add n each time'.

Example task

Continue this sequence: 3, 7, 11, 15, ?, ?. What is the rule?

Model response: 19, 23. The rule is add 4 each time.

Developing

Generating terms of a sequence from a rule and finding pairs of values that satisfy a two-variable equation.

Example task

Find all pairs of positive whole numbers where a + b = 8.

Model response: 1+7, 2+6, 3+5, 4+4, 5+3, 6+2, 7+1.

Expected

Describing linear sequences algebraically, enumerating solutions to two-variable equations, and solving problems involving sequences.

Example task

A sequence starts at 5 and adds 3 each time. Is 50 in the sequence? Explain.

Model response: Terms: 5, 8, 11, 14... Each term is 3n + 2 (where n starts at 1). For 50: 3n + 2 = 50, 3n = 48, n = 16. Yes, 50 is the 16th term.

CPA Stages

concrete

Building linear patterns with physical objects (tiles, matchsticks, cubes) and recording the number in each term, then finding all integer pairs that satisfy two-variable equations using counters

Transition: Child describes the common difference, predicts any term, and enumerates all positive integer solutions of a two-variable equation systematically

pictorial

Drawing pattern sequences and recording in tables, writing the term-to-term rule, and plotting solution pairs of two-variable equations on a coordinate grid

Transition: Child generates sequences from rules and enumerates solutions on a coordinate grid, noticing the linear pattern

abstract

Working with sequences and two-variable equations abstractly: finding the nth term rule (informally), predicting terms, and finding all solutions within a range

Transition: Child finds any term of a linear sequence and systematically enumerates solutions to two-variable equations

Delivery rationale

Upper primary maths (Y6) — most pupils at pictorial/abstract stage. AI can deliver with virtual representations.

Mathematical Reasoning and Justification

process AI Direct

MA-Y6-C030

Mastery of mathematical reasoning at Year 6 means pupils can construct and communicate a logical mathematical argument, explain why a procedure works (not just how), and use examples and counter-examples to investigate conjectures. A fully secure pupil can distinguish between a demonstration (showing that something is true in a specific case) and a proof (showing that it must always be true), and uses correct mathematical language and notation to communicate their reasoning clearly and precisely.

Teaching guidance

Embed reasoning tasks throughout all mathematical content rather than treating reasoning as a separate topic. Use prompts such as 'Always, Sometimes, Never' (e.g., is it always true that multiplying two numbers gives a larger answer?), 'Prove it' challenges, and 'Find the error in this reasoning' activities. Teach pupils to use language precisely: 'The answer is always even because...' rather than 'I think it's even'. Connect to the algebra domain: algebraic notation is a tool for expressing general mathematical truths. Require pupils to write mathematical explanations as complete sentences that would be understood by someone who has not seen the working.

Vocabulary: reason, justify, explain, prove, conjecture, counter-example, always, sometimes, never, generalise, argument, logical
Common misconceptions

Pupils often confuse explanation ('this is what I did') with justification ('this is why it must work'). Checking a rule with one or two examples is often mistaken for proof. Some pupils communicate mathematical reasoning in informal or ambiguous language that does not precisely convey their thinking. The distinction between 'showing' and 'proving' needs explicit teaching with examples from familiar mathematical content.

Difficulty levels

Entry

Explaining what they did and why in a single-step calculation using mathematical vocabulary.

Example task

Explain why you added 37 and 28 to solve the problem about apples.

Model response: I added because the problem said 'altogether', which means combining two groups. 37 + 28 = 65 apples altogether.

Developing

Using examples and counter-examples to investigate whether a mathematical statement is always, sometimes or never true.

Example task

Is this always, sometimes or never true: 'Multiplying two numbers gives a bigger answer'?

Model response: Sometimes true. True: 3 × 4 = 12 (bigger than both). False: 0.5 × 6 = 3 (smaller than 6). Also false: 0 × 5 = 0 (not bigger than 5). So it depends on the numbers.

Expected

Constructing a chain of logical reasoning to prove or disprove a conjecture, distinguishing proof from demonstration.

Example task

Prove that the sum of three consecutive numbers is always a multiple of 3.

Model response: Let the three consecutive numbers be n, n+1, n+2. Their sum = n + (n+1) + (n+2) = 3n + 3 = 3(n+1). Since 3(n+1) is 3 times a whole number, it is always a multiple of 3.

CPA Stages

concrete

Using physical examples and counter-examples to test conjectures: building arrays, sorting shapes, or testing number properties with real objects

Transition: Child tests conjectures systematically using examples and counter-examples and refines statements based on findings

pictorial

Recording mathematical arguments on paper: writing 'if...then' statements, drawing diagrams to support reasoning, and using algebraic notation to express general rules

Transition: Child writes mathematical justifications that explain WHY something must be true, not just that it IS true in specific cases

abstract

Constructing and communicating mathematical arguments using precise language, generalising from patterns, and distinguishing between examples and proof

Transition: Child constructs logical arguments using algebraic reasoning and clearly distinguishes between demonstration and proof

Delivery rationale

Upper primary maths (Y6) — most pupils at pictorial/abstract stage. AI can deliver with virtual representations.