Guidance to DP Physics Internal Assessment
The individual investigation (20% of your final IB score) is marked using five criteria:
Personal engagement
Exploration
Analysis
Evaluation
Communication
These criteria are weighted as follows:
Personal
engagement
Exploration
Analysis
Evaluation
Communication
Total
2 (8%)
6 (25%)
6 (25%)
6 (25%)
4 (17%)
24
In the first part of the course, you will carry out various formative tasks to help you understand the assessment
criteria.
' The guidance in this document was compiled by Elisa Jimenez and is the product of discussions with several DP Group 4 teachers (Anderson,
Davison, Fotiu, Vincent, Webber, and many more) as well as advice given in various publications (Brown and Ford, 2015; Neuss, 2007).
Personal engagement
This criterion assesses the extent to which the student engages with the exploration and makes it their own. Personal
engagement may be recognized in different attributes and skills. These could include addressing personal interests
or showing evidence of independent thinking, creativity or initiative in the designing, implementation, or presentation
of the investigation.
Specific guidance for Personal Engagement
-
Your topic of study should spark curiosity and should not be immediately obvious.
Outline why you chose this investigation topic, why you think it's interesting and important.
-
Explain how your investigation builds on what you have learnt in class.
-
-
You should adapt your practical experiences in class to come up with a method of your own. This does not
mean that you have to invent a method from scratch, but you must demonstrate some degree of personal input
in designing the investigation. Please do not take a standard experiment found in a textbook or online.
Your report should demonstrate at least 10 hours' worth of practical work.
Your report should show a clear focus on your research question throughout.
-
Focus on the research question.
Exploration
This criterion assesses the extent to which the student establishes the scientific
context for the work, states a clear and focused research question and uses
concepts and techniques appropriate to the Diploma Programme level. Where
appropriate, this criterion also assesses awareness of safety, environmental,
and ethical considerations.
Specific guidance for Exploration
1.
Title
Be descriptive. “The effect of concentration on index of refraction” is not a
descriptive title.
2.
Research question
 This can be phrased as a question or a clear statement of
purpose. It must be clear and concise.
 Include the independent and dependent variables, as well
as the reaction or system being studied.
3.
Backqround information

Explain the reasoning for your choice of investigation, previous
work done in this area, and any important theories, laws,
equations that may be relevant (i.e., those that might be
tested/verified in your experiment).

This section should explain to a reader with some
background in physics the information needed in order to
understand the significance of your investigation and
appreciate the importance of your results. Explain your
choice of variables, in light of what you have discussed
above.

Focus on your chosen independent and dependent variables
and research question. State your sources appropriately. No
Wikipedia No Yahoo Answers.
4. Hypothesis
 Not formally required, but you are encouraged to include it in
order to support your background information and later on, your
conclusion.

Write a hypothesis and predict the relationship between the
independent and dependent variables and explain it
scientifically. Sketch a graph of the relationship you expect to
find.
5.
Variables
 Identify the independent (manipulated) variable and dependent
(measured) variable.
 Both the independent and dependent variables should be quantitative
(numerical).

Please note that the dependent variable is the measured variable,
it is not inferred. For example, in a practical investigating the effect
of temperature on index of refraction, index of refraction is not the
dependent variable. Possible dependent variables might be the
angle of refraction. (This can then be used to find the index of
refraction.)

List the controlled variables. When determining controlled
variables, think beyond same equipment, room temperature
and pressure. Identify key variables that would affect the
results or your ability to answer the research question.

Briefly explain how you will keep the controlled variables constant.
If there is a variable that should be controlled but doing so is
practically impossible (e.g. room temperature), then you should
at least plan to monitor it.

Watch out for the term amount. It has a precise meaning in
physics, which is moles of a substance. If you mean volume or
mass or concentration, say so.
6.
Materials
 Write a detailed list of materials (include units, sizes and
uncertainties, quantities and concentrations).
 You will be expected to prepare your own apparatus, so list the
equipment and substances required to do so.
7.
Safetv

8.
Consider (i) health hazards, (ii) disposal and (iii) minimizing the effect of
hazards of equipment or chemicals that you will be using
Preliminary Experiments

You must carry out some preliminary trials to establish a detailed plan.

The range and intervals of the independent variable should be justified
using preliminary work or scientific research (which must be fully
referenced).
If you have based your method on one you found elsewhere, then you
should make a comment to this effect, reference the source, and describe

the ways in which you amended it to suit the purposes of your investigation.
9.
Method










This can be written in prose or in steps.
The method should contain enough information to allow the reader to
replicate your experiment.
Avoid long lists of steps that refer back to each other;” Repeat steps 4
to 9 with the substances listed in step 11” is very confusing. If your
method is excessively long, you must condense it.
A diagram or annotated photograph should be included to show the
set-up —a good-quality diagram will often save you several
sentences.
Plan to collect sufficient data. The rule of thumb is at least five trials and
at least 5 data points. Above all, you must ensure sufficient data is
planned for. ”Sufficient data” constitutes enough data to allow you to
address the research question.
Plan to collect data over a suitable range.
The independent variable should be
accurately manipulated.
The dependent variable should be accurately and systematically measured.
All the controlled variables must be stated clearly and maintained at a
constant value or at the very least, monitored.
Include a control group, if applicable.
Analysis
This criterion assesses the extent to which the student's report provides evidence that the
student has selected, recorded, processed, and interpreted the data in ways that are
relevant to the research question and can support a conclusion.
Specific guidance for Analysis
1. Data collection
 Record the relevant controlled variables (e.g. room temperature.
 Record all raw data, units and uncertainties in a neat table with a title (A table to show...)
Independent variable in the first column.
 Column headings should be clear and precise and include SI units and suitable uncertainties.
 Decimal places should be consistent with the equipment's precision.
 Any anomalies should be flagged (e.g. asterisk, highlighting, footnote, etc) and excluded
from the average. If this is the case, include a comment to this effect under the table.
 Include relevant observations (colour changes, gas/bubbles formation, precipitate
formation, changes in temperature, etc).
2. Data processing
 Always process and show your results mathematically in some way.
 Guide your reader through the calculations and graphs by commenting on each part of your processing.
Include headings for calculations, tables and graphs.
 Calculations:
o
o
Show sample calculations by stating any formulae used and the substituted values.
Report your answer to the correct number of significant figures and state the unit.
o
State any assumptions you make.
 Random error
o Propagate uncertainties to estimate the random error and again, one sample calculation.
o Check the precision of your results matches that of their uncertainties.
 Graphs
O
Independent variable along the x-axis and dependent variable along the y-axis.
O
Write a suitable title for your graph(s).
O
Plot a big graph and smooth line or curve of best fit and error bars.
O
Choose appropriate scales, and write detailed axis labels, with units and uncertainties.
O
Calculate the gradient in decimal form and with units. Show how the gradient calculation is
done, even if you have used technology to find it.
o Determine the R2 value for the correlation (there is no need to show the calculation here)
o Anomalies should be graphed but not taken into consideration when drawing a line of best fit.
 Percentage error - Calculate your percentage error (if possible). Cite the source of the literature value.

No Wikipedia. No Yahoo Answers.
 Processed data table - Present your processed data in a neat table.
3. Data analysis
 Describe the results: comment on what the graph shows. Is there a correlation?
 Comment on the direction of the correlation (positive/negative) and whether it is linear or nonlinear.
 Comment on the strength of the correlation. Justify your statement by referring to the r2 value.
 Comment on the variability (similarity between trials) and spread (closeness to the line of best
fit) of the data.
 Comment on any anomalies and briefly speculate on what might have caused them.
 Comment on the impact of random error (propagated uncertainty, error bars).
 Comment on the impact of systematic error (error beyond the propagated uncertainty, y-intercept)
 Assess the relative impacts of systematic and random errors on the analysis.
 This written analysis must allow a conclusion to be drawn. Refer to your observations whenever
possible.
 Be critical — do not blindly accept an Excel polynomial fit and “good” r2 value. Consider whether
your graphical analysis makes sense in the context of your investigation.
Evaluation
This criterion assesses the extent to which the student's report provides evidence of
evaluation of the investigation and the results with regard to the research question and the
accepted scientific context.
Specific guidance for Evaluation
1. Conclusion

Describe trends and patterns revealed by the data.

Explain these trends and patterns scientifically. Cite your
sources appropriately.

Answer your research question. Describe and justify it clearly.


Refer to your observations whenever possible.
Compare your results to the expected outcome — calculate a percentage error if
possible, or at the very least discuss whether the graphs' characteristics (linearity,
equation, intercepts, etc) are well aligned with your expectations.
2. Evaluation

Outline the strengths of the investigation.

Comment on limitations and weaknesses of the investigation. Remember
carelessness should not be a source of error. Things to think about:

o
o
Were all the controlled variables adequately controlled?
Was the independent variable adequately manipulated?
o
o
Was the range of the independent variable suitable?
Was the dependent variable adequately measured'*
o
What are the limitations of the data?
Consider the limitations of your methodology: is there a better reaction system or
group substances that could be used in this investigation? ls there an alternative
procedure that could be used to explore the relationship between these
variables?

identify each limitation or weakness as systematic, random, or due to assumptions.

Explain how the limitations and weaknesses might have affected your results (be
specific, would the calculated value be higher/lower? How would they affect the
graph?).

Make specific suggestions for improvement that could realistically be achieved in a
school lab.

If you can't think of a way to eliminate errors altogether, try to at least minimize them.

Be specific about which equipment could be used. Avoid comments that say
things like” more sophisticated and accurate measuring devices should be
used“.
Remember to discuss suggestions for further enquiry.

You might want to include a table like the one below:
Limitation or weakness
We relied on human reaction time to
determine when the chemical
reaction was complete.
This is a random error because it can
affect the results in both directions.
etc
Effect on results
greater uncertainty associated
with the time measurements
and therefore greater random
error. This explains the large
spread of data, particularly at
lower temperatures when the
reaction was slower.
Suggestions for improvement
use a turbidimeter to sample
the
reaction mixture at different
times and measure the
opacity. The time taken to
reach a certain opacity at
each temperature could
then be extrapolated from a
graph of opacity vs time
- repeat trials twice more to
minimise
random errors
Communication
This criterion assesses whether the investigation is presented and reported in a way that supports
effective communication of the focus, process and outcomes.
Specific guidance for Communication
1. Clarity
-
Go through and check whether your investigation focuses sharply on the research
question.
Use headings for tables, graphs and diagrams to aid interpretation.
Narrate your data analysis — it will help communication and help you
write your conclusion and evaluation.
Ask your friends and family members to proofread your report for clarity,
conciseness, coherence, and focus.
2. Formatting
 Include section subtitles and numbered headings for diagrams, tables and
graphs.
 Font size 10-12, normal margins, 1.5 or double-spaced.
 Graphs, calculations, and diagrams can be drawn by hand and scanned in,
provided the images are clear.
 Be mindful of significant figures and units.
3. Referencing
 In-text (parenthetical) citations should be embedded in the text
every time you:
o
Quote a source directly
o
Paraphrase someone else‘s ideas
o Use a diagram or picture that is not yours
 Full references should be stated at the end of your investigation. The in-text
citation sources must be included in full in the references section.
 References do not count towards the page count.