The key words found in each question are the essential element to unlocking all HSC science exams. The first thing you should do, before putting pen to paper, is identify the key words and what the question requires.

The content, design and structure of your answers should be guided by what each key word requires you to do, such as 'outline', 'contrast' or 'describe'. Some questions may also ask 'how'. This means 'explain how', requiring 'cause and effect' statements in your answer with a connecting link word such as 'because' or 'so'.

In each exam the extended response questions enable you to demonstrate your wide knowledge of the course and to draw on and explain concepts across the Prescribed Focus Areas and the Domain of the syllabus.

Knowledge of first hand investigations in is essential as is the ability to describe a procedure, interpret data and communicate results.

These questions also require you to demonstrate a clear understanding of the concepts of designing a fair test, identifying dependent and independent variables and discussing the concepts of validity, reliability and accuracy of results. Also, refer to the Science Course Performance Descriptions to guide you.

Finally, as well as the syllabuses, refer to the Science Course Performance Band Descriptions, assessment and reporting materials, past exam papers, marking guidelines and notes from the marking centre, on the BOSTES site and Students Online for more study resources and exam advice.

Kerry Sheehan, Science Inspector, BOSTES.

Chemistry

To achieve highly in Chemistry you must know the syllabus well, use its language and be able to apply your knowledge to answer questions at the required level. For example, you may be asked about:

• Heat of Combustion. The question may be descriptive, about the investigation that you performed and/or a calculationbased.
• Transuranic elements. Here you may be asked to provide a description only.
• When attempting questions involving knowledge of first hand investigations you should provide specific details of the quantities, chemicals and equipment used. Examples of different levels of responses here include:
• "Add bromine to ethylene." This is a simple statement that does not demonstrate whether you have done the experiment, since bromine could be bromine liquid or bromine water.
• "Add bromine water to 1-hexene." This demonstrates your deeper understanding since appropriate specific chemicals are identified.
• "Add 3 drops of bromine water to a test tube that contains about 1 cm depth of 1-hexene." This demonstrates an extensive understanding since you have identi- fied the appropriate quantities, chemicals and equipment.

Using the language of Chemistry appropriately in all responses demonstrates a more thorough understanding. Some questions may not specifically ask you to include a chemical equation, however, students who show a deep understanding of chemistry always use equations and chemical formulae. Examples of varying responses here include:

• Stating that "An acid is neutralised by a base" demonstrates a very general understanding.
• Describing that "Hydrochloric acid is neutralised by sodium hydroxide" demonstrates a deeper understanding.
• Writing a balanced equation for the neutralisation reaction or a net ionic equation for this reaction demonstrates a thorough understanding of the chemistry involved.

Follow any specific instructions when developing your response, for example:

• "Include a diagram in your answer."
• "Making use of data from the table."

Visit the BOSTES site for more information about Chemistry.

Anna Davis, Science Coordinator, Casimir Catholic College, Marrickville