Think about sodium hydroxide (NaOH) solution at a macroscopic, sub-microscopic and symbolic level
Use this resource to explore the different ways to represent and describe sodium hydroxide solution. Learners consider how the solution can be represented using particle diagrams as well as the symbolic representation of units of concentration.
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Use this student worksheet to introduce concentration of solutions at three different conceptual levels based on learners’ observations.
View and download more Johnstone's triangle worksheets
Learning objectives
- Describe how to identify whether a beaker contains sodium hydroxide or water.
- Recognise the unit symbols used for concentration.
- Interpret particle diagrams of solutions in terms of how they represent concentration.
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.
Further reading
Read more about how to use Johnstone’s triangle in your teaching with these articles:
- Develop deeper understanding with models
- Improve students’ understanding with Johnstone’s triangle
- Practical ideas for using Johnstone’s triangle
Norman Reid’s book The Johnstone triangle: the key to understanding chemistry provides an more in-depth overview, the first chapter is available to read online.
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.
Next steps
To further develop learner’s thinking in all areas of Johnstone’s triangle, try our Developing understanding of concentration and mass worksheet. These worksheets include icons in the margin referring to the conceptual level of thinking needed to answer the question.
Downloads
Concentration of NaOH Johnstone's triangle student sheet
Handout | PDF, Size 0.19 mbConcentration of NaOH Johnstone's triangle teacher notes and answers
Handout | PDF, Size 0.21 mbConcentration of NaOH Johnstone's triangle student sheet
Editable handout | Word, Size 0.54 mbConcentration of NaOH Johnstone's triangle teacher notes and answers
Editable handout | Word, Size 0.54 mb
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