## Key Ideas > [!abstract] Core Concepts > > - **Break complex routines into smallest teachable parts**: Isolate individual knowledge components (atoms) that can be assessed and taught separately > - **Familiar atoms, unfamiliar combinations**: During instruction, students should recognise all components so attention focuses on how they fit together > - **Systematic progression from atoms to routines**: Teach/assess atoms individually, then chain together to build complex procedures ## Definition **Atomisation**: Breaking routines down into their smallest constituent parts (atoms) that can be assessed or taught separately, ensuring students have secure foundations before combining them into complex procedures. ## Connected To [[Prior Knowledge]] | [[Worked Examples]] | [[I Do]] | [[We Do]] | [[Cognitive Load Theory]] | [[Part-whole approach]] --- ## Why atomisation matters Atomisation addresses the challenge of teaching complex procedures without overwhelming working memory. When students learn new procedures, their attention should focus on how familiar atoms fit together, not on learning individual atoms simultaneously (Sweller, van Merriënboer, & Paas, 2019). Each unfamiliar atom consumes working memory resources needed to understand the combination (Cowan, 2001). Without atomisation, common problems emerge. Demonstrations extend beyond six minutes because students do not recognise components. Students become confused during explanations and cannot follow the logic. Follow-up questions reveal poor understanding despite clear demonstrations. Atomisation supports instruction by ensuring students recognise components before combining them. During demonstrations, familiarity with individual elements allows attention to focus on how components combine rather than what each component means. ## The four-step atomisation process Effective atomisation follows a systematic sequence from example selection through atom identification, prior knowledge assessment, and isolated teaching of new components. ### Step 1: Choose a good example Example selection affects learning outcomes. Avoid repeated elements in examples; using the same numbers multiple times creates pattern confusion and false generalisation. Keep arithmetic simple with manageable numbers that focus attention on core concepts rather than calculation. Start with general examples rather than "easy" ones that hide the process, as this reveals the true procedure complexity students will encounter. Vary critical features by changing one key element between examples to highlight distinctions and prevent overgeneralisation. Poor example choice undermines atomisation of the underlying procedure. ### Step 2: Break down into atoms Write the complete worked example and solution. Identify the knowledge students need to progress from each line to the next; each discrete piece of knowledge becomes an atom. Include "invisible" atoms such as decisions, recognition steps, and mental processes that students must perform but that may not appear explicitly in written work. ### Step 3: Identify prior knowledge (★) Star (★) any atoms students have encountered before. These become prerequisite knowledge to assess (Dochy, Segers, & Buehl, 1999). Plan one targeted question per starred atom, using examples most relevant to the planned demonstration. ### Step 4: Teach new atoms separately Teach novel atoms in isolation before combining them. Use appropriate teaching methods based on atom type (described below). For complex procedures, chain atoms together gradually. Ensure 80% or higher success before moving to the full routine (Wilson et al., 2019). ## Types of atoms and teaching methods Different atom types require different teaching approaches. The five main categories are category atoms, fact atoms, transformation atoms, comparative atoms, and routine atoms. ### Category atoms (Cat) Category atoms answer "Is this a ...?" questions with yes or no responses. Examples include "Is this a trapezium?" or "Can we use sine rule?" The teaching sequence follows a negative-positive-positive-positive-negative (N-P-P-P-N) pattern. Begin with a negative example to establish boundaries, then present a positive example with minimal change from the negative. Follow with two positive examples showing maximal differences in different directions to demonstrate range. End with a negative example that differs minimally from a positive to reinforce boundaries. Let examples do the work with minimal explanation. Include one negative example per critical feature. Present the definition last, after students have seen the pattern. Test using an unpredictable sequence to ensure genuine understanding rather than pattern recognition. ### Fact atoms (F) Fact atoms are formulas, theorems, and properties that students must remember, such as "Interior angles sum to 180°" or "Area = ½ × base × height". The teaching sequence follows an explain-frame-reframe-rehearse pattern. Provide the full statement with context, then frame it with sentence starters like "The formula for ___ is..." and use cold calling for completion. Rearrange the wording to build flexibility in recall. Finally, students rehearse with partners to strengthen retention. ### Transformation atoms (T) Transformation atoms involve input changed to output in obvious ways, such as adding fractions, expanding brackets, or solving simple equations. Use silent modelling with one to three examples where the teacher demonstrates without narration. Keep arithmetic simple with manageable numbers. Change one element per example to focus attention on critical variation. Test progressively using minimal changes first, then resets to new starting points, then longer progressions. ### Comparative atoms (Com) Comparative atoms require students to witness change by observing before and after states. Examples include speed, gradient, and density changes. The teaching sequence uses a positive-positive-negative-negative (P-P-N-N) pattern. Present two positive examples showing the change, followed by two negative examples showing what does not constitute change. Highlight the transformation through visual or physical demonstration. ### Routine atoms (R) Routine atoms are multi-step procedures that function as atoms within larger routines, such as solving equations or finding areas. These require the full I Do-We Do approach and need their own atomisation before being incorporated into more complex procedures. ## Advanced implementation: chaining atoms Complex procedures with multiple atoms require gradual combination to prevent cognitive overload. The chaining process begins by teaching and assessing two to three atoms individually until students demonstrate secure understanding. Chain those atoms together and practice until fluent. Add more atoms to the chain systematically, continuing until the full routine is achieved. ### Example: algebraic fractions Consider the routine of adding $\frac{2x}{x+1} + \frac{3}{x-2}$. Analysis identifies five atoms: adding numerical fractions (★), finding LCM of algebraic expressions (new), expanding brackets (★), collecting like terms (★), and recognising simplification opportunities (★). The starred atoms represent prior knowledge that should be assessed with quick questions. The LCM of algebraic expressions is new and requires isolated teaching. Chaining proceeds from LCM alone, to LCM with expanding, to adding collecting terms, before finally demonstrating the complete routine. ## Decision framework for prerequisites When encountering an atom students have seen before, check understanding with a targeted question. If 80% or more respond correctly, continue to the next atom. If fewer than 80% respond correctly, provide quick reteaching and recheck. If students still struggle, more extensive reteaching is needed before proceeding. ## Implementation guidelines Atomisation occurs per demonstration rather than per lesson. Each I Do within a learning sequence requires its own atomisation. Duration varies depending on the number of new atoms and student prior knowledge. Initial effort pays dividends in clearer instruction and better understanding. Use an 80% threshold as the minimum success rate before proceeding (Wilson et al., 2019; Rosenshine, 2012). Base decisions on actual student responses rather than assumptions. Apply the same standards regardless of class "ability" level. Common mistakes undermine atomisation effectiveness. Skipping atomisation makes demonstrations confusing. Bundling new atoms creates cognitive overload. Assuming prior knowledge leaves students without necessary foundations. Atomising per lesson rather than per demonstration misses specific needs. Ignoring the 80% rule creates weak foundations. ## Quality indicators Successful atomisation produces observable outcomes. Demonstrations flow smoothly in around 30 seconds. Students complete follow-up questions successfully with minimal confusion during guided practice. Students appear confident and successful. Explanations are clear enough for all students to follow. Warning signs indicate problems with atomisation. Demonstrations extend beyond three to four minutes. Multiple hands go up during explanation. Students perform poorly on immediate practice and look confused or frustrated. Teachers find themselves re-explaining multiple times. ## Practical example breakdown Consider the routine of solving 2(x + 3) = 14. Atom analysis identifies four components, all likely prior knowledge: distributive property (★), collecting like terms (★), inverse operations (★), and order of operations for checking (★). Quick assessment questions such as "What's 2 × (x + 3)?" and "How do we isolate x?" reveal understanding levels. If 80% or more respond successfully, proceed to demonstration. If fewer than 80% respond correctly, provide targeted reteaching of weak atoms before demonstrating the complete routine. This systematic approach ensures students can focus on the procedure rather than struggling with components. ## References Cowan, N. (2001). 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