All articles by Helen Harden

Ideas

Build stronger particle understanding

2026-04-02T07:32:00Z

Three simple strategies to minimise misconceptions and solidify learners’ understanding of the particle model

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Interpreting chemical equations for ionic compounds | Developing understanding | 14–16

Help your learners develop mental models of what is represented in balanced chemical equation for ionic compounds with this resource, including teacher notes and a student worksheet 

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Balancing chemical equations using magnesium and oxygen | Johnstone’s triangle worksheets | 14–16 years

Introduce Johnstone’s triangle with these teacher notes and a student worksheet to help learners gain a deeper understanding of balancing chemical equations 

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Moles of xenon | Johnstone’s triangle worksheets | 14–16 years

Introduce Johnstone’s triangle as a method of calculating the number of moles of xenon from a given volume of gas

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Moles and volume | Developing understanding | 14–16 years

Deepen your learners’ understanding of the idea that equal volumes of gases contain an equal number of molecules with this worksheet

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Moles of gold | Johnstone’s triangle worksheets | 14–16 years

Connect macroscopic, sub-microscopic and symbolic understanding of calculations involving moles and mass with Johnstone’s triangle

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Moles and mass | Developing understanding | 14–16 years

Develop understanding of the relationship between the mass of one mole, the number of moles and the mass of a substance

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Reactant and product substances | Developing understanding | 11–14

Use these worksheets to secure and deepen your learners’ understanding of reactants and products in chemical changes

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Iron and sulfur reaction | Johnstone’s triangle | 11–14

Develop your learners’ understanding of reactants and products at different conceptual levels, using an iron and sulfur reaction as an example

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C, O and Co | Johnstone’s triangle | 11–14 years

Develop your learners’ understanding of symbols and formulas at different conceptual levels by comparing the symbolic representations of carbon monoxide and cobalt

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Symbols and formulas | Developing understanding | 11–14 years

Develop your learners’ understanding of what is represented by symbols and chemical formulas

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Interpreting chemical equations | Developing understanding | 14–16 years

Deepen learners’ understanding of interpreting chemical equations by exploring the topic at different conceptual levels

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Balancing chemical equations using hydrogen and oxygen | Johnstone’s triangle worksheets | 14–16 years

Introduce Johnstone’s triangle to help learners gain a deeper understanding of balancing chemical equations

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Relative atomic mass of boron | Johnstone’s triangle worksheets | 14–16 years

Use Johnstone’s triangle to help learners think about the relative atomic mass of boron 

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Concentration and mass | Developing understanding | 14–16 years

Encourage learners to deepen their understanding of concentration and mass from the macroscopic to sub-microscopic level

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Concentration of sodium hydroxide | Johnstone’s triangle worksheets | 14–16 years

Think about sodium hydroxide (NaOH) solution at a macroscopic, sub-microscopic and symbolic level

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Reacting ratios: masses | Developing understanding | 14–16 years

Develop learners’ understanding of the ratio of the very large number of atoms or molecules in balanced chemical equations

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Extracting tin from tin oxide | Johnstone’s triangle worksheets | 14–16 years

Introduce calculations using reacting masses in the context of extracting tin from tin oxide 

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Diffusion and chemical reactions | Developing understanding | 11–14 years

Use this worksheet to deepen understanding of diffusion and chemical reactions and how these processes are represented 

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Diffusion and dissolving | Developing understanding | 11–14 years

Deepen learners’ understanding of diffusion and dissolving with this worksheet exploring different conceptual levels of thinking