## Suggestions for teachers and students in undertaking Practical Investigation

If you would like to:

- Contribute a new question,
- provide an extra response to a current question, or
- Offer a tip for undertaking the practical investigation

then please email it to **Vicphysics**.

## FAQs

- Students hope to find a relationship between variables. If their results show no relationship, does their grade suffer as a consequence?
- If a student’s graphs do not reveal any discernable pattern capable of further analysis, then they can instead identify possible sources of error or explanations for the anomalous results and suggest ways of modifying their procedure. It can also be suggested that if the student progressively analyses the data on a daily basis, then anomalies can be quickly identified and changes made.

- Should the student be expected to provide a physics explanation of the results or the phenomenon they are investigating?
- This is probably too much to ask of a Year 12 student doing a 3 – 4 week practical investigation. There is not enough time for a student, having identified relationships between variables to then explore a variety of resources to construct a coherent physics explanation of them. It is also likely some some topics for investigation might involve physics beyond Year 12.

- How do you manage and assess the plan if students are working in pairs?
- If two students come to you with a topic, which gets your approval, then they are likely to go away and do some planning. However, if you decide to formally assess the plans under test conditions, which is a useful idea, you may wish to conduct that task fairly soon after topics have been approved. With the large amount of detail required in a typical plan, it is likely that there will be differences between the two students’ plans. This scenario also presupposes that you don’t distribute the template for the plan ahead of time.

- How many trials are enough? How many data points are sufficient for analysis?
- Depending on the ease with which trials can be repeated, five seems reasonable at this level. Three trials would be insufficient, unless, the measurements were very consistent. Five data points does not normally indicate a trend, at least seven seems appropriate, unless the functionality is clearly evident.

- Is there a preferred method for determining error bars?
- The important aspect is that a consistent method is used and it is described in the log book with an example. One method to determine the size of the error bar is to use the larger of the two differences of the max and min data values from the average. Alternatively if there is a large number of measurements, then the use of the standard deviation is a possibility.

## Tips

Teachers

- Consider letting students do a preliminary exploration with the equipment for their topic before they prepare their plan. This may help them formulate variables and their intended method.

Students

- Model the phenomenon to be investigated with a simplified version, e.g. for example if comparing compressability of dry, wet and wetter sand, use a small steel ball, rather than your foot, or if investigating the sweet spot of a cricket bat, use a small rectangular piece of wood.
- Model sporting impacts in the vertical direction, so that the speed of impact can be easily determined from the drop height of the ball.
- To help parachutes fall in a straight line, use a guide line of fishing line passing through the air hole in the centre of the parachute and the ring of plasticine attached at the bottom.

For the website with list of topics and advice on Posters, click **here**.