7.9 - Assignment Skills
What the assignment is
- Alongside the question paper, National 5 Physics has an assignment: coursework in which you research a physics topic, run an experiment, handle the data, and write it up as a report.
- It's worth about 20% of the course award.
The two stages
- Research - Settle on an aim, find out the physics behind it, carry out an experiment, and gather comparison data from the internet, books, or journals.
- Report - Write a structured report under controlled conditions, including a table, graph, analysis, conclusion, and evaluation.
Choosing an aim and the underlying physics
- The assignment starts with a title (what the report is about) and an aim (a clear statement of what you're trying to find out).
- A good aim names the two variables and reads as "how does X affect Y" (e.g. "to find out how the length of a nichrome wire affects its resistance").
- Keep the aim narrow enough to investigate in the time you have, and make sure it needs an experiment.
The underlying physics
- Set out the physics that explains why you expect your result.
- For a wire experiment: current is a flow of charge, in a longer wire the charge carriers make more collisions with the metal ions, giving higher resistance ().
- The background physics should explain the aim you chose, not everything you know about the broad topic.
Collecting and handling data
- Make it a fair test - Change only the independent variable and keep all control variables constant. Only then can a change in the result be put down to that variable alone, making the result valid.
- Repeat for reliability - Take each reading more than once and calculate the mean. This reduces the effect of anomalies and makes your results reliable.
- Record raw data - Record the actual measurements you took straight into a table, across a wide enough range to plot a graph.
Comparison data
- You must gather published data from the internet, a book, or a journal to compare your experimental results against.
- Record the full reference at the time so you can credit it in the report.
Calculated values
Any values worked out from your raw data (such as means or calculated resistances) go into the table with their own column headings and units.
Presenting your data
The table
- The variable you change goes in the first column, with its values in order.
- Include a column for each repeat of the measured variable, plus columns for any calculated values.
- Write every heading as "quantity / unit".
- Record all raw readings in a column to the same precision.
The graph
- Line graph - Use when the independent variable is continuous (numerical values that can take any value in between, such as length or temperature). Plot points as crosses and draw a line of best fit.
- Bar chart - Use when the independent variable is discrete or categoric (separate groups with no values in between, such as different materials).
- Label both axes with the quantity and its unit, and choose a linear scale that fills at least half the grid.
Analysing data and drawing a conclusion
Compare with your source
- State whether your experimental results agree with the published source data.
- If they're consistently higher or lower, state the difference and give a reason (such as contact resistance or wire heating).
Describe the trend
State the relationship shown by your graph and table, quoting values from both axes to back it up.
The conclusion answers the aim
- The conclusion must directly answer the original aim using your own results.
- For example: "As the length of the nichrome wire increased from 20 cm to 100 cm, its resistance increased from 4.2 Ω to 21 Ω; the graph was a straight line through the origin, so resistance is directly proportional to length."
Evaluating the investigation
The evaluation must discuss a specific factor affecting the reliability, accuracy, or precision of your results and pair it with an improvement:
- Reliability - How closely repeat readings agree with each other.
- Accuracy - How close your values are to the true values, shown by comparing against your source data.
- Precision - How finely your instruments could measure.
Weaknesses and improvements
Name a specific feature of your experiment rather than generic "human error":
- A wire that warmed up during readings - improved by switching off the circuit between measurements.
- Wire length judged by eye at the clips - improved by taping a metre stick directly beneath the wire.
Writing up and referencing
Report structure
- Title and aim
- Underlying physics
- Description of the experiment
- Raw data table
- Calculated values
- Comparison data from a source
- Graph
- Analysis
- Conclusion
- Evaluation
- References
Referencing
- Credit the source of your comparison data so a reader can find it:
- Website - Title and full URL.
- Book - Title and author.
- Write the report in your own words using correct physics terms and units.
Common exam questions
Question 1
Roughly how much of the National 5 course award is the assignment worth?
About 20% - a fifth of the grade - so it carries the credit for skills the written paper cannot test, such as collecting your own data and referencing sources.
Question 2
What are the two stages of the assignment?
Research, in which you settle on an aim, carry out an experiment that gives you measurements, and gather comparison data from a source; and the report, written up under controlled conditions.
Question 3
What makes a good aim for the assignment?
One that names both variables, is narrow enough to test, and needs an experiment, reading as "how does X affect Y", such as "how does the length of a nichrome wire affect its resistance".
Question 4
Besides your own experimental results, what other data must the report contain?
Comparison data from the internet, a book, or a journal, gathered so you can compare your own results against it, together with a reference for where it came from.
Question 5
Why should you repeat your readings and take a mean in the assignment?
Because a single reading might be an anomaly, and repeating shows whether the readings agree with each other, which is what makes the result reliable.
Question 6
You collected the resistance of a wire at six different lengths. Should you draw a line graph or a bar chart?
A line graph, because length is a continuous variable with values in between; plot the points as crosses and draw a line of best fit through them.
Question 7
What does the analysis section of a physics assignment have to do that the question paper never asks for?
Compare your own experimental results against the data you found from your internet or literature source, saying whether they agree and explaining any difference.
Question 8
The evaluation asks for a factor affecting the reliability, accuracy, or precision of your results. What makes a weak answer?
One that says only "it could have been more accurate" or blames "human error". A strong answer names a real feature of your experiment, says which of the three it affects, and gives an improvement that would reduce it.
Question 9
Why must you reference the source you used for your comparison data?
Because any information or data that is not your own must be credited, so a reader can see where it came from and check it; referencing is a required part of the write-up.