AS 91167 annotated exemplars

This annotated exemplar is intended for teacher use only. Annotated exemplars are extracts of student evidence, with commentary, that explain key parts of a standard. These help teachers make assessment judgements at the grade boundaries.

Download all exemplars and commentary [PDF, 280 KB]

TKI Chemistry assessment resources (external link)

For Excellence, the student needs to demonstrate comprehensive understanding of oxidation-reduction.

This involves justifying, evaluating, comparing and contrasting, or analysing links between oxidation-reduction reactions, observations and equations. This requires the consistent use of chemistry vocabulary, symbols and conventions.

This student has identified and described oxidation and reduction reactions by using change in oxidation numbers (1). Species have been linked to observations (2). Both half equations are balanced (3) and the correctly balanced overall equation is written (4). There is consistent use of chemistry vocabulary, symbols and conventions.

For a more secure Excellence, the student could indicate the actual oxidation number change when Fe2+ is oxidised to Fe3+ (5).

For Merit, the student needs to demonstrate in-depth understanding of oxidation-reduction.

This involves making and explaining links between oxidation-reduction reactions, observations and equations. This requires explanations that use chemistry vocabulary, symbols and conventions.

This student has identified and described oxidation and reduction reactions by stating the actual number of electrons lost and gained (1). Species have been linked to observations (2). Both half equations are correctly balanced (3). Chemistry vocabulary, symbols and conventions are used in explanations.

To reach Excellence, the student could correctly balance the full equation (4).

For Merit, the student needs to demonstrate in-depth understanding of oxidation-reduction.

This involves making and explaining links between oxidation-reduction reactions, observations and equations. This requires explanations that use chemistry vocabulary, symbols and conventions.

The student has identified and described the reduction half reaction by stating that electrons are gained and has identified that the oxidation number decreases (1). Species have been linked to observations for the reduction half reaction (2). The balanced reduction half equation is written (3). Chemistry vocabulary, symbols and conventions are used in explanations.

For a more secure Merit, the student could indicate the number of electrons gained in the reduction half reaction or the oxidation number change for both species (4).

For Achieved, the student needs to demonstrate understanding of oxidation-reduction.   

This involves describing, identifying, naming, giving an account of oxidation-reduction and describing oxidation-reduction reactions. This requires the use of chemistry vocabulary, symbols and conventions.

The student has identified the formulae of species from observations (colour of species) (1). The reduction reaction is correctly identified and described by the gain of electrons (2). Chemistry vocabulary, symbols and conventions are used.

To reach Merit, the student could provide the balanced reduction half equation (3).

For Achieved, the student needs to demonstrate understanding of oxidation-reduction.   

This involves describing, identifying, naming, giving an account of oxidation-reduction and describing oxidation-reduction reactions. This requires the use of chemistry vocabulary, symbols and conventions.

The student has identified the formulae of species from observations (colour of species) for both half reactions (1). The reduction half reaction is correctly identified and described by the gain of electrons (2). Chemistry vocabulary, symbols and conventions are used.

For a more secure Achieved, the student could provide evidence for oxidation number change or loss or gain of electrons. This evidence could be in the form of half equations.

For Achieved, the student needs to demonstrate understanding of oxidation-reduction.

This involves describing, identifying, naming, giving an account of oxidation-reduction and describing oxidation-reduction reactions. This requires the use of chemistry vocabulary, symbols and conventions.

The student has identified the formulae of species from observations (colour of species) for both half reactions (1). The reduction half reaction is correctly identified and described by the gain of electrons (2). Chemistry vocabulary is used (2).

To reach Achieved, the student could identify the oxidation reaction with reasons (3).