Whether it be Biology, Chemistry, or the field in question, Physics, practical scientific investigations are one of the cornerstones of most if not all of these science-based subjects. As such, it is not merely a suggestion, but a necessity for high-achieving students to ensure they can effectively demonstrate their investigative skills. That being said, for many students, scientific investigations can be long, arduous, and often confusing battles of trying to bulletproof your work, or even simply stay under the word limit.

To address this issue, we at Complete have created this step-by-step guide to aid VCE Physics students in conquering this final SAC.

However, make no mistake - this guide can also be applied to other science subjects.

1. Planning your Investigation

A solid investigation needs a solid foundation of course. The very first step students must take is to decide what your experiment will entail. It is often recommended to undertake an investigation into motion due to its relative simplicity compared to other topics, such as the dual nature of light.

Before settling on an idea, ask yourself:

• What materials will you need for the investigation to be doable?
• Will the results be easily measurable? (Not spending too much time on error calculations)
• What can be discussed? (Potential errors, oversights, extraneous variables, etc.)
• Can you confidently explain the phenomena occurring?

These four, simple questions should gauge the feasibility of your idea of an experiment. Once you are happy with the answers, you are able to move onto the next step.

2. Asking Question(s)

The question we need to ask now is a specific and testable one, meaning:

• Testable: Able to be answered by collecting data
• Specific: Focused on a single variable combination (IV and DV)

For example:

• “How does the mass of a toy car affect its stopping distance?” Good
• “Is the toy car’s motion affected by its mass?” Bad

The latter example is not suitable for two reasons. First, it is phrased as ayes/no question, which limits the depth of investigation. Second, the term 'motion' is too vague and does not clearly define what aspect is being measured. In contrast, the former example is specific and testable, as it clearly identifies both the independent variable (mass of a toy car) and the dependent variable (stopping distance).

It may not seem important for now, but this question will form the basis of your entire investigation and create the following sections.

It is also at this stage that you will want to ensure you are recording all your work down suitably in a practical logbook. As for some logbook tips:

• Make sure each entry is dated and timestamped
• Label sections clearly and make it easy to read
• Do not forget to note everything that happens into the logbook, even if you did nothing in a particular session

Think of the logbook like your evidence in court - that is, the court of your final mark!

3.  Identify Variables

Now that your basic question is created, we will want to clearly identify each variable:

• Independent variable (IV): What is changed ‍
• Dependent variable (DV): What is measured (Remember that it may not be affected)
• Controlled variables (CV): What is maintained throughout trials

4.  Form an Aim and Hypothesis

Moving on from the variables, we now need to determine why this experiment is being performed and state our educated guess on what the outcome will be.

• Aim: Simply the purpose of your investigation
  “To investigate the effect of a toy car’s mass on its stopping distance”‍
• Hypothesis: How you think the IV will affect the DV and in what direction.
  “If the mass of the toy car is increased, then so will the stopping distance”

It is most important to remember that simplicity is key when it comes to these two statements. For the hypothesis, be sure to clearly state the direction of change in the dependent variable, such as whether it increases or decreases. Avoid using vague or generic terms such as 'affects', as they do not specify precisely how the variables are related.

5.  Designing and Conducting the Experiment

Now it is time for the main event – the experiment itself. However, it is easy to get jumbled up in the process of what to do first:

1. Choose equipment.
   Ensure, or at least confirm the precision and calibration of the instruments used as this will be important for discussion later. Record all the equipment used accurately; note the quantities, scale, or variant of the item in a bulleted list.
   In terms of sensible equipment choices, it would be detrimental to your precision if you used a 1.0 m long ruler to measure the length of an ant, or got your friend to count time in their head rather than utilising a stopwatch.
   
2. Write the method.
   Simply write a numbered, step-by-step method that succinctly describes what is being done. The easiest way to maintain quality is to put yourself in the shoes of someone else reading it – would they understand, and what questions could they have? It needs to be as reproducible as possible.
   
3. Do the experiment.
   There is not much specific to say here – you are the expert of your own experiment. That being said, it may be useful to take photos for the next step.
   It goes without saying but being precise and repeating trials at least thrice is absolutely essential to obtaining useable results.
   
4. Record data in tables
   This again seems like it should be obvious but it needs to be reiterated more often than you might think. Make your data as readable possible. Often the simplest way to do this is to follow the norm; use tables.
   
5. Account for uncertainty.
   It is no longer junior science, so simply including the measured values is no longer satisfactory. You need to record the uncertainty of each measurement and in addition, justify the uncertainty number in your logbook. Whether this is taking half of the smallest measurement of a ruler, or the stated uncertainty of a force sensor, it needs to all be recorded.      
   
6. Draw a labelled diagram.
   This is where the photos taken prior may have come in handy. While its commonly recommended to only draw a diagram for complex experiments, we would suggest doing it anyways to use less words in the method section of the poster.

6.  Presenting the Data

If you recorded your data in tables, there is not too much extra to do in this section aside from graphical representation.

If they do not already, ensure that tables…

• Have clear titles
• Have the independent variable in the first column
• Units in all headings
• Inclusion of uncertainties and averages of trials

For example:

Hardly a complicated table, but one that nonetheless includes all the requirements.

As for graphs, the type will be dependent on the data type.

• If both IV and DV are numerical, then make a scatter plot
• If the IV is categorical, then make a bar graph

Regardless of type however, some basic requirements still apply:

• A clear title
• Labelled axes with clearly defined units
• IV on the x-axis, DV on the y-axis
• If appropriate, a line of best fit
• Some representation of uncertainty (typically error bars)

7.  Error Analysis

Before moving onto result analysis, it is important to also identify the sources of error and how they affect validity, accuracy, precision and reliability of the experiment. Doing so at this stage not only primes oneself for the writing of a smooth discussion later on but also makes this step itself easier with the experiment still fresh in your mind.

• Validity: Did the experiment actually test what it claimed to test?
  Can be improved by better controlling extraneous variables, and only test the IV
  
• Accuracy: How close a measured value is to the ‘true value’?
  Can be improved by minimising systematic error – calibrate equipment and employ careful experimental technique
  
• Precision: How close repeated measured values are close to each other?
  Repeat trials, use equipment with smaller uncertainty, improve technique
• Reliability: Are the results consistent across trials?
  Check all outliers and identify their cause, use averages not raw data, repeat trials

It is also important to categorise your errors into the two major types:

• Random: Unpredictable due to environmental fluctuations. Affects precision.
• Systematic: Faulty equipment or method that consistently affects accuracy.
• Human: A consistent inaccuracy in the method. Technically a type of systematic error and as such affects accuracy.

8.  Interpreting Results

Bulk of your writing will be analysing the outcomes of your trials and linking it back to the original hypothesis and aim. It simply is not enough to just state the results – we need to reflect on our experience.

Ask yourself:

• Was the hypothesis supported?
• Summarise the results and key findings into no more than 1-3 sentences
• What errors affected your data (carry over from last step)
• How did the errors affect the outcome?
• How can the experimental design be improved?

9.  Creating the Poster

With the previous steps completed, there is only a few specific things left to do to complete the components of the poster:

Write the introduction:

A self-explanatory section. This section introduces the scientific concepts and background information required to understand the purpose and outcome of your investigation. As such, it should include:

• Variable identification (IV, DV, CV)
• Concept name
• Concept explanation
• Relevant formulas
• If applicable, existing studies
• Theoretical outcomes, potentially from studies
• Rationale – why is this experiment justified?

Following this structure, it should be quite difficult to miss any key parts of the introduction. If still in doubt, simply ask yourself what someone completely new to the concepts explored in your investigation could ask.

Write the discussion:

This will mostly be a carry-over of Step 8 but in a more organised fashion. A layout we would recommend following is:

• Summarise key findings briefly
• Explain, using relevant concepts and formulas, how the findings may have arisen
• Explore confounding results and explain potential causes
• Consider the effects of specific errors on experimental design (precision, accuracy, etc.)
• Consider the limitations of the data and/or experimental design and how it influenced the outcome(s)

This section will likely contain the most number of words.

Write the conclusion:

Once again, mostly a repackaging of Step 8 that focuses on rounding out your findings. Simply consider:

• Was the aim completed?
• Was the hypothesis supported?
• Once again summarise key findings
• Suggest improvement or further investigation

The conclusion should be short and snappy. The contents of the very final sentence are completely up to you, but the first three steps above are critical to scoring any marks for this section. However, a common way to finish scientific conclusions is to make a statement about the future of your line of research.

References:

When explaining scientific concepts or using information from other sources, you must cite where the information came from. Most VCE teachers are not strict about which referencing style you use, but consistency is key. Two commonly used styles are:

• APA style – uses in-text citations like (Author’s Last Name, Year) and a full reference list at the end.
• Harvard style – very similar to APA, also uses in-text citations and includes the full source details.

A simple format like the following is usually acceptable for posters:

• In-text citation: (Author’s Last Name, Year)
• Full reference: Author’s Last Name, First Name. Title of Source. Year.

If in doubt, check with your teacher or refer to a referencing guide for APA or Harvard style.

The poster itself:

All that is left now is to put everything onto the poster.

This is a layout which should be familiar to many of you – the triple column. While it is not a hard rule that you need to follow, simple is best – as with most things in this assessment. This is a standardised layout in, and even outside of VCE in the scientific world that emphasises organisation and readability.

Conclusion

In summary, each of the steps to go through the scientific investigation are:

1. Planning your investigation
2. Asking investigation question
3. Identifying variables
4. Creating aim and hypothesis
5. Creating and performing the experiment
6. Presenting the data
7. Error Analysis
8. Interpreting results
9. Creating the poster

And so, this marks to end of this lengthy, but ‘Complete’ guide. If you have made it this far through our guide, congratulations – you will now have most of the knowledge required to master the VCE Physics scientific investigation SAC.

However, for those still seeking more knowledge, we have also published a detailed walkthrough of a past exemplar scientific poster, which can be found at the link below:

For even more assistance with anything VCE Physics related, we offer a range of tutoring programs as a company with a dedicated focus in helping students of all calibres thrive in this often challenging subject.

With the assistance of an extensive resource bank of questions, worked solutions, tips and tricks directly from past cohort-topping tutors and tailored group classes taught by experienced tutors specialising in Physics, we guarantee enrolment with Complete VCE Education to be one of the simplest, but effective choices you could make in elevating your future physics study score!

Please feel free to contact us if you have any queries through our website. We look forward to seeing you in the classroom, whether that be in Melbourne CBD or on Zoom, in the near future!