This Swedish literature review discusses students’ understanding of matter and some of the misconceptions that have been identified in the relevant literature. This compilation of information is used to suggest some possible approaches to overcome misconceptions.

Learners’ ideas

• During chemical reactions, a substance 'disappears'.
• During chemical reactions, a substance is 'displaced' rather than a new substance made.
• Most children at the age of 14 still firmly adhere to the idea that each individual substance is conserved.
• During chemical reactions, a substance is 'transmuted', i.e. a substance turns into energy, energy turns into a substance, or one substance into another.
• Students may use the terms 'liquid' and 'water' synonymously.
• Some students think that any material melting into a transparent liquid is becoming water.
• Some students will intuitively apply a principle of conservation of 'matter', but not appreciate that this implies conservation of 'weight' (students may be confused between mass and weight).
• Some students claim that smoke or gas does not weigh anything, is light, or is lighter than a solid.
• Some students consider air and gas to be two separate things.
• Some students do not understand that air can be enclosed and that air has weight.
• Some students think that air cannot exert pressure, or that it can only do so when being actively compressed.
• Some students believe air to be incompressible.
• Some students believe that gases behave like liquids, collecting at the bottom of a vessel rather than expanding to fill it.
• Some students believe that atoms could vary in form, for instance, they could be square or rectangular.
• Some students believe that there is no vacuum between atoms in a substance.
• Some students project macroscopic properties onto atoms and molecules.
• Some students believe that atoms/molecules/particles are embedded in continuous 'matter'.
• Some students thought that compound substances (e.g., water) were thought to be made up of individual atoms in the ratio given by their chemical formula, rather than molecules in this configuration.
• Some students thought that powders were not examples of solids.

Suggestions

• Make a distinction between models and observations, clearly explaining parts of the model. This may help students to avoid conflating different models/depictions of the atoms (circles, balls, shells, nuclei) and to separate model behaviour from actual atomic behaviour.
• Try to maintain a clear distinction between substances and atoms/molecules and be aware of many textbooks' failure to do so.
• Be aware of the potential of textbook illustrations to mislead, especially with regard to intermolecular/interatomic spacing in different states of matter.
• Be aware that textbook phrasing may mislead, especially with regard to the macroscopic properties of a substance propagating down to its microscopic constituents.

Study Structure

Aims

To structure and discuss what is known about pupils' conceptions of matter and its transformation.

Evidence collection

Evidence is collected via a review of relevant literature.