All articles by Helen Harden

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Bioethanol | Johnstone’s triangle | 11–14 years

Connect understanding about the macroscopic properties of elements and compounds at a sub-microscopic and symbolic level

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Filtration | Developing understanding | 11–14 years

Support learners to develop secure mental models of how filtration can be used to separate mixtures

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Filtering muddy water | Johnstone’s triangle | 11–14 years

Use Johnstone’s triangle to explain how filtration can be used to separate mixtures

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Limiting and excess reactants: quantitative | Developing understanding | 14–16 years

Develop learners quantitative understanding of limiting and excess reactants with the support of bar diagrams

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Bondio ïonig | Datblygu dealltwriaeth | 14–16 oed

Datblygu dealltwriaeth y dysgwyr o ddellt ïonig drwy gymharu cynrychioliadau 2D a 3D 

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Decomposition of calcium carbonate | Johnstone’s triangle worksheets | 14–16 years

Think about reacting masses and gas volumes in the context of a decomposition reaction

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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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Reacting ratios: gas volumes | Developing understanding | 14–16 years

Connect learners’ ideas about balanced equations, the ratio of atoms and moles and the volume of reactants and products

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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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Excess copper oxide | Johnstone’s triangle worksheets | 14–16 years

Explore the reaction of sulfuric acid with excess reactant copper oxide at three conceptual levels with Johnstone’s triangle

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Limiting and excess reactants (qualitative) | Developing understanding | 14–16 years

Introduce limiting and excess reactants using an analogy of ice cream and ice cream cones

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Determining unknown concentration | Johnstone’s triangle worksheets | 14–16 years

Guide learners to connect their thinking about calculating unknown concentrations following a titration

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

Learners connect their understanding of dissolved ions, concentration and how chemicals are labelled with this single-page worksheet

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Concentration and moles | Developing understanding | 14–16 years

Support learners to develop secure mental models of how concentration is measured and calculated in mol/dm³

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Word equations | Developing understanding | 11–14 years

Use this worksheet to improve your learners’ understanding of writing and interpreting word 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 relative atomic mass and the abundance of different isotopes

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Màs atomig cymharol boron | Taflenni gwaith triongl Johnstone | 14–16 oed

Defnyddiwch driongl Johnstone i helpu’r dysgwyr i feddwl am fàs atomig cymharol boron

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Fertiliser yield | Johnstone’s triangle worksheets | 14–16 years

Help learners calculate the actual and theoretical yield of ammonium sulfate using Johnstone’s triangle

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Yield | Developing understanding | 14–16 years

Part of the Johnstone’s triangle series, this resource includes teacher notes and a student worksheet to help learners understand the difference between actual and theoretical yield

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Sodium and chlorine reaction | Johnstone’s triangle | 11–14 years

Strengthen learners’ understanding of the connection between word equations and chemical reactions