Helen Harden
Helen is a former head of chemistry at an 11–18 comprehensive school. She has an in-depth understanding of the science curriculum from primary through to secondary level with a specialist focus on chemistry. Helen has developed award winning resources and currently provides curriculum consultancy and resource development services to UK-based and international organisations.
Helen was formerly the chemistry lead for the University of York's Best Evidence Science Teaching (BEST) project. Her extensive reading of the chemistry education research literature on misconceptions informs much of her work today.
Helen is an active member and former chair of the Association for Science Education. She is currently commissioning editor of ASE’s School Science Review journal. Helen is also a member of the Royal Society of Chemistry and was a member of the 11–16 Curriculum and Assessment Working Group.
IdeasBuild stronger particle understanding
Three simple strategies to minimise misconceptions and solidify learners’ understanding of the particle model
ResourceInterpreting 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
ResourceBalancing 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
ResourceMoles 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
ResourceMoles 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
ResourceMoles 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
ResourceMoles 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
ResourceReactant and product substances | Developing understanding | 11–14
Use these worksheets to secure and deepen your learners’ understanding of reactants and products in chemical changes
ResourceIron 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
ResourceC, 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
ResourceSymbols and formulas | Developing understanding | 11–14 years
Develop your learners’ understanding of what is represented by symbols and chemical formulas
ResourceInterpreting chemical equations | Developing understanding | 14–16 years
Deepen learners’ understanding of interpreting chemical equations by exploring the topic at different conceptual levels
ResourceBalancing 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
ResourceRelative 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
ResourceConcentration and mass | Developing understanding | 14–16 years
Encourage learners to deepen their understanding of concentration and mass from the macroscopic to sub-microscopic level
ResourceConcentration of sodium hydroxide | Johnstone’s triangle worksheets | 14–16 years
Think about sodium hydroxide (NaOH) solution at a macroscopic, sub-microscopic and symbolic level
ResourceReacting 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
ResourceExtracting 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
ResourceDiffusion 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
ResourceDiffusion and dissolving | Developing understanding | 11–14 years
Deepen learners’ understanding of diffusion and dissolving with this worksheet exploring different conceptual levels of thinking