Physics

90180 (Physics 1.1) version 3.

Carry out a practical physics investigation with direction

Exemplars of Student Work

The following exemplars, based on actual student work, are intended to exemplify the boundaries between Achieved, Merit and Excellence for this achievement standard. The Achievement Criteria for the standard are: •Achievement: Carry out a practical physics investigation•Achievement with Merit: Carry out a quality practical physics investigation•Achievement with Excellence: Carry out and evaluate a quality practical physics investigationThe explanatory notes (EN) of the standard give guidance about typical evidence that contributes to a particular grade:For Achievement, a practical physics investigation will involve (from EN5): •a statement of the purpose – this may be an aim, testable question, prediction, or hypothesis based on a scientific idea•identification of a range for the independent variable or sample•measurement of the dependent variable or the collection of data•collecting, recording and processing data relevant to the purpose•a conclusion based on interpretation of the processed data.For Merit, a quality physics science investigation enables a valid conclusion to be reached. This would normally involve (from EN6):•a statement of the purpose – this may be an aim, testable question, prediction, or hypothesis based on a scientific idea•a method that describes: a valid range for the independent variable or sample; a description of and/or control of other variables; the collection of data with consideration of factors such as sampling, bias, and/or sources of error•the recording and processing of data to enable a trend or pattern (or absence) to be determined•a valid conclusion based on the processed data in relation to the purpose of the investigation.For Excellence, an evaluation is required. Evaluate means to justify the conclusion in terms of the method used. Justification will involve, where relevant, consideration of the (from EN7):•reliability of the data•validity of the method•physics ideas.

Exemplar 1: Not Achieved

This is a clear Not Achieved.

A weak statement of purpose.

The plan does not identify a valid range for the independent variable, although the data table shows a valid range has been used.

Data (times for three swings?) have been collected and recorded. Measurements were repeated three times, but averages not found. Period times are graphed, but not listed in the data table. Time units are not given. Graph axes are not labelled. Horizontal axis scale is not linear.

The conclusion does not involve any interpretation of the data, but is merely a restatement of the data. .

Exemplar 2: Achieved (low)

This is a low Achieved.

Acceptable statement of purpose. The plan does not identify a valid range for the independent variable, although the data table shows a valid range has been used. Control of other variables (amplitude of swing, pendulum used) is mentioned.

Data has been collected, recorded and processed to find the period. Period times calculated correctly.

The conclusion is based on interpretation of the processed data. However the conclusion is stated in general terms only. No repetition and averaging of measurements was done, and data points are not accurately positioned on the graph.

Exemplar 3: Achieved (high)

This is a high Achieved.

Acceptable statement of purpose. Independent variable is identified as steepness, but measured in terms of number of books used to build ramp. Control of variables is limited to components (car, ramp etc), rather than physical quantities such as mass, amplitude, friction, etc.

A conclusion based on an interpretation of the processed data is given, but for Merit this must be related to the purpose of the investigation. The purpose was defined in relation to steepness or gradient of the ramp, but the stated conclusion does not explicitly relate to steepness.

Physics ideas in the discussion are flawed (“greater force pushing it”).

Exemplar 4: Merit (low)

This is a low Merit.

Purpose is given as a hypothesis.

Method describes a valid range for the independent variable. Control of other variables is described (angle of pendulum at start, mass of pendulum, air currents).

Data is measured and recorded. Data is processed to find the period and the average period.

A valid conclusion is given in relation to the purpose (“The longer the string the longer time it takes for it to swing… This proves my hypothesis.”)

Evaluation / discussion does not justify the conclusion, but merely mentions difficulties or things that could be done differently in future.

Exemplar 5: Merit (high)

This is a high Merit.

The evaluation mentions the reliability of the method (“each gradient was tested three times then averaged”). Validity of the data is considered (“However the results are not completely reliable as the car’s axles were uneven…”). Physics ideas are very well discussed (energy conversion, friction).

This does not gain Excellence as only three values of the independent variable were used. This could be sufficient if a clear trend was seen, not evident in the results. Thus the conclusion cannot be justified as it is not adequately established in terms of sufficient reliable data.

While a valid range for the independent variable is normally expected for a Merit grade (EN6), the overall standard of the evidence here is at a strong Merit level.

Exemplar 6: Excellence

This is a solid Excellence.

Purpose is given as a testable question.

A valid range for the independent variable is given, and control of other variables is discussed (marble mass, diameter, floor friction). Data is measured, recorded and processed by averaging and graphing.

A valid conclusion is given, based on the data in relation to the purpose (“The steeper the slope is, the greater the distance the marble will roll”).

The discussion gives an evaluation which considers the reliability of the data (“Results were repeatable, except for one outlier…The data was concordant”); validity of the method (“We averaged results to even out any variations… We took enough readings (3) to allow a valid trend”); and physics ideas (energy transformation).