Balancing chemical equations using hydrogen and oxygen | Johnstone’s triangle

With this resource, learners recognise chemical formulas and symbols in equations and describe what is being shown in a balanced chemical equation. 

Learning objectives 

1. Recognise the chemical formulas used in the equation. 
2. Interpret the state symbols used in the equation. 
3. Describe what is shown by the balanced chemical equation. 

How to use Johnstone’s triangle

Use Johnstone’s triangle to develop learners’ thinking about scientific concepts at three different conceptual levels:

• Macroscopic: what we can see. Think about the properties that we can observe, measure and record.
• Sub-microscopic: smaller than we can see. Think about the particle or atomic level.
• Symbolic: representations. Think about how we represent chemical ideas including symbols and diagrams. 

For learners to gain a deeper awareness of a topic, they need to understand it at all three levels.

When introducing a topic, do not try to introduce all of the levels of thinking at once. This will overload working memory. Instead complete the triangle over a series of lessons, beginning with the macroscopic level and introducing other levels, in turn, once secure.

All of the levels are interrelated, for example, learners need visual representation of the sub-microscopic in order to develop mental models of the particle or atomic level.

Scaffolding

It is important to share the structure of the triangle with learners prior to use. Tell them why you want them to use the triangle and how it will help them to develop their understanding. Use an ‘I try, we try, you try’ approach when you are introducing Johnstone’s triangle for the first time.

More resources 

To further develop learner’s thinking in all areas of Johnstone’s triangle, try our Developing understanding of interpreting equations worksheet.  This resource aims to develop learners’ understanding of how balanced chemical equations provide information such as the state of reactants and products and the ratio in which atoms and molecules react or are formed. The worksheet includes icons in the margin referring to the conceptual level of thinking needed to answer the question.