What Should You Put in an HSC Science Logbook?

Your final science report says the reaction took 18.6 seconds. But can you show which measurements produced that result, what the temperature actually was, and why you changed the method halfway through the investigation?

If all you have is a polished report and a graph, you might struggle to answer. The evidence behind your conclusion has disappeared.

An HSC science logbook should contain the dated record of what you planned, did, observed, measured, changed, and decided. It should preserve your original data, explain where information came from, and show how your investigation developed over time.

The key idea is simple: a logbook records what actually happened, not what you wish had happened.

01A logbook is not the same as a scientific report

Imagine a flight recorder. It captures the sequence of events, including unexpected changes and problems. A scientific logbook serves a similar purpose, although you have to record the information yourself rather than relying on an automatic device.

A scientific report has a different job. It presents the investigation in a logical, organised way, usually after the work is complete.

A report might contain an average calculated from five trials. Your logbook should contain the five original measurements, including any unusual results.

Would a beautifully formatted graph be enough to prove that an investigation was conducted carefully?

No. The graph shows a processed representation of the data. It cannot, by itself, tell you whether a measurement was repeated, whether the apparatus changed, or whether an unusual result was excluded.

02What does NESA actually require?

Before deciding what to put in your logbook, separate NESA requirements from your school’s assessment instructions and practical recommendations.

These are not interchangeable.

NESA requirements

The NSW Education Standards Authority (NESA) sets the syllabus requirements, course outcomes, and framework for school-based assessment.

For Physics and Chemistry, Working Scientifically is an important part of the course. It covers:

• Questioning and predicting
• Planning investigations
• Conducting investigations
• Processing data and information
• Analysing data and information
• Problem-solving
• Communicating scientific information

A logbook can provide useful evidence of how you developed these skills.

However, NESA’s course requirements do not prescribe one universal logbook template that every HSC Physics and Chemistry student must follow.

The course requirements specify scientific investigations and depth studies. Schools determine the details of their assessment tasks within NESA’s rules.

There are also differences between syllabus editions.

As at 10 November 2026:

The 2025 Physics and Chemistry syllabuses also require at least one depth study in each of Year 11 and Year 12.

These are course requirements, not logbook formatting rules. Check the syllabus that applies to your enrolment cohort rather than assuming the two subjects transition in the same year.

Official syllabus information:

• NESA Physics Stage 6 (2017)
• NESA Physics 11-12 (2025)
• NESA Chemistry Stage 6 (2017)
• NESA Chemistry 11-12 (2025)

Your school sets the assessment details

NESA’s ACE Rules give schools authority to determine the number, type, and weighting of their in-school assessment tasks, subject to NESA requirements.

Your school may therefore specify:

• Whether a logbook is compulsory.
• Whether it must be handwritten or digital.
• Whether you submit the entire logbook or selected entries.
• Whether teacher checkpoints or signatures are required.
• How individual contributions to group investigations must be documented.
• What evidence must accompany your final submission.

Read your assessment notification and marking criteria carefully.

A logbook might be an assessed component of a depth study, supporting evidence for a report, or a record that your teacher checks during the investigation. These arrangements are not necessarily identical between schools.

For a broader explanation of the investigation itself, see What Is a Depth Study in HSC Science?.

03What should you actually put in your logbook?

A useful logbook should allow someone to reconstruct the important stages of your investigation.

There are six things worth recording.

1. Dated observations and activities

Every entry should have a date. For practical investigations, include the time or session where it helps establish the sequence of events.

Start an entry with:

• Date and time
• Investigation title or question
• What you intended to investigate during that session
• Equipment and materials used
• Who participated, where relevant

For example:

Date: 12 May 2026

Time: 2:10 pm-2:35 pm

Investigation: Investigating the effect of ramp angle on the travel time of a trolley.

Activity: Set up the track, checked the photogates, and collected preliminary measurements at three different ramp angles.

This establishes when the work occurred and what was actually completed.

Don’t write an entire page of background theory every time you enter the laboratory. Your logbook should focus on the progress of the investigation.

2. Your actual method and experimental conditions

Your planned method and your actual method might not be identical.

Suppose you planned to heat a solution to 40°C but could only maintain 38°C during the experiment.

Your logbook should record 38°C.

It should not quietly retain the planned temperature as though the experiment followed the original instructions perfectly.

Record important experimental details, including:

• Equipment and apparatus
• Independent and dependent variables
• Controlled variables
• Actual concentrations, masses, volumes, and temperatures
• Instrument settings and measurement resolution
• Relevant environmental conditions
• Changes to the original procedure

Include labelled sketches when the arrangement of equipment matters.

For example, a Physics investigation involving a trolley and photogates should record the distance between the gates, the release position, and the direction of travel.

A Chemistry investigation might need the actual solution concentrations, volumes, reaction temperature, and equipment used.

The goal is to make the experimental conditions clear enough that another student could understand what you did.

3. Raw data and observations

This is one of the most important parts of your logbook.

Raw data means the original information collected during an investigation, before you process or manipulate it.

Suppose you measure the time taken for an object to travel a fixed distance.

Your readings are:

Your logbook should preserve all three measurements.

Don’t replace them with just the mean:

\[ \bar{t}=\frac{1.42+1.45+1.39}{3} \]

\[ \bar{t}=1.42\text{ s} \]

The mean is useful, but it is processed data. The original readings are the evidence from which it was calculated.

Your raw-data record should include:

• Individual measurements, not just averages.
• Appropriate units.
• Instrument precision or resolution.
• Qualitative observations.
• Unexpected results.
• Any unusual conditions during a measurement.

Also distinguish between an observation and an interpretation.

For example:

Observation: The solution changed from colourless to pale yellow after approximately 40 seconds.

Interpretation: The colour change may indicate that the reaction has reached the chosen endpoint.

The first describes what you observed. The second explains what you think it means.

Both are useful, but they are not the same thing.

4. Where your data came from

This is called data provenance.

Provenance means being able to trace information back to its original source.

There are two important situations.

Primary data

This is information you collect yourself.

Record:

• Who collected the measurements.
• When they were collected.
• What equipment was used.
• How the measurements were obtained.
• Relevant instrument settings and calibration details.
• Where the original digital records are stored.

If a photogate produces a CSV file, record its filename and preserve the original file.

Secondary data

This is information collected by someone else, such as a published dataset, research paper, or government database.

Record:

• Author or organisation.
• Title of the publication or dataset.
• Publication date or dataset version, where available.
• Original URL or DOI.
• Date you accessed or downloaded it.
• Specific table, figure, page, or data range used.
• Any filtering, selection, or processing you performed.

Don’t write that you measured something yourself when you actually obtained it from another source.

This distinction becomes especially important when your investigation combines experimental measurements with published information.

5. Changes, mistakes, and unexpected results

A good logbook does not pretend that every experiment went according to plan.

In fact, unexpected results often make the record more useful.

Suppose your trolley repeatedly stops at the same point on a track. You inspect the apparatus and discover that one section is slightly raised.

Record:

• What happened.
• Which trial was affected.
• What you observed.
• What you think caused the problem.
• What you changed.
• Why you made that change.
• Which measurements were collected before and after the change.

Be careful with corrections.

If you write down an incorrect value, don’t erase it or make it disappear.

For a handwritten logbook, draw a single line through the incorrect entry so that it remains readable. Add the corrected value, date, and initials where appropriate.

For a digital logbook, use version history or a change record. Keep original data files rather than overwriting them.

Never change an earlier entry to make it look as though you knew something at the time that you only discovered later.

6. Decisions and next steps

A logbook should also explain how you decided what to do next.

For example:

The first trial at 5° produced an incomplete result because the trolley stopped at a raised section of track. The track joint was reseated. As this changed the apparatus, the full series of measurements was repeated to maintain comparable conditions.

This is much more useful than simply writing:

Fixed track and repeated experiment.

The first entry explains the problem, the decision, and its effect on the investigation.

When recording an important decision, use this structure:

Also finish each session with a short note about the next step.

This could be repeating a measurement, checking a calculation, locating a missing data source, or investigating an unexpected result.

04An annotated example: what a useful logbook entry looks like

Let’s put these ideas together.

Imagine you’re investigating how the angle of an inclined track affects the time taken for a trolley to travel a fixed distance.

You want to determine whether increasing the angle decreases the travel time.

The following is an illustrative example of how the logbook could look. The measurements are fictional teaching data, not results from an actual experiment or NESA sample.

Investigation question: How does ramp angle affect the time taken for a trolley to travel 1.00 m?

Date: 12 May 2026

Time: 2:10 pm-2:35 pm

Equipment:

• Adjustable inclined track.
• Trolley.
• Two photogates.
• Digital angle gauge.
• Photogate timer.

Experimental conditions:

The distance between the two photogates was 1.00 m. The same trolley, track surface, release position, and photogate positions were used throughout.

The trolley was released from rest without an additional push.

The angle gauge had a resolution of 0.1°, and the timer displayed measurements to 0.01 s.

Raw measurements:

Unexpected observation:

During the initial attempt at 5.0°, the trolley stopped at a raised section of the track before reaching the second photogate.

No valid travel time was obtained.

Modification:

The track joint was reseated to remove the obstruction. The original failed attempt was retained in the notes but not included in the comparison table.

Because the apparatus had changed, the full measurement series was repeated at all three angles.

Data provenance:

Measurements were collected directly using the photogate timer. The original timer export was saved as ramp_2026-05-12.csv. The values in the notebook were transcribed from that file.

Initial observation:

The recorded travel times decreased as the ramp angle increased.

Next step:

Repeat the measurements in another session and check that the track joint remains aligned.

Notice what makes this entry useful.

It doesn’t just show the final pattern. It explains how the measurements were obtained, what went wrong, and why the experiment was repeated.

It also avoids making a stronger conclusion than the evidence supports. One session suggests a relationship, but further repeats would help establish how reliable that pattern is.

05Two common situations that need careful recording

06A practical logbook checklist

Before finishing a laboratory session or investigation session, check the following.

• [ ] Have I dated the entry?
• [ ] Have I recorded what I actually did?
• [ ] Have I documented the important experimental conditions?
• [ ] Have I preserved every original measurement?
• [ ] Have I included units and instrument details?
• [ ] Have I recorded unusual observations and failed trials?
• [ ] Can I identify where every secondary-data value came from?
• [ ] Have I documented changes to the original method?
• [ ] Have I explained important decisions?
• [ ] Have I identified the next step?

You don’t need to write an essay after every lesson. A concise entry containing the relevant evidence is far more useful than several pages of vague commentary.

The following distinction is worth remembering:

A logbook should be complete, not necessarily beautiful.

A few crossed-out words, an unexpected result, or a revised method are not signs of poor scientific work. They are part of an honest record of an investigation.

07Questions and solutions

Use these questions to check whether you can apply the principles rather than simply remember a list of things to include.

Question 1

A student measures the mass of a sample three times:

• 4.82 g
• 4.85 g
• 4.83 g

Their final report includes only the average mass of 4.83 g.

What information should their logbook contain?

Solution 1

The logbook should contain all three original measurements, with the calculated average recorded separately.

The three readings are raw data. The average is processed data.

The student should also record the date, balance used, measurement units, relevant instrument precision, and experimental conditions.

Keeping the individual readings allows someone to assess the variation between measurements. If only the average survives, that information is lost.

Question 2

A Chemistry student investigates the effect of temperature on reaction time.

At 25°C, the student records three reaction times:

During the third trial, the student notices that the magnetic stirrer stopped for approximately eight seconds.

Explain how the student should record this result and whether it should be included in the final average.

Solution 2

The 52 s measurement must remain in the raw-data record, but it should be identified as an affected trial.

The student should document that the stirrer stopped, when the interruption occurred, and whether stirring was part of the required experimental procedure.

If constant stirring was necessary to maintain the intended conditions, the third trial is not directly comparable with the first two.

The student can calculate a provisional mean from the two unaffected readings:

\[ \bar{t}=\frac{34+35}{2} \]

\[ \bar{t}=34.5\text{ s} \]

However, this is based on only two valid trials.

The student should repeat the affected trial under the original conditions and record the replacement measurement separately.

It would be tempting to remove 52 s simply because it differs from the other results. The actual justification, however, is the documented interruption to the experimental procedure.

Also, the student should avoid claiming that the stirrer interruption definitely caused the entire difference. It is a plausible explanation, but the logbook should distinguish observed evidence from interpretation.

Question 3

Two Physics groups investigate how ramp angle affects the travel time of a trolley over the same distance.

Group A uses photogates. Group B uses a handheld stopwatch.

Both groups record their measurements in seconds and investigate the same ramp angles.

A student combines both groups’ measurements into one dataset and calculates a single average for each angle.

Is this automatically a valid approach? Explain what should be recorded and considered before combining the data.

Solution 3

No. The two datasets should not automatically be treated as equivalent measurements.

Although both groups use seconds and investigate the same variable, their measurement methods differ.

Photogates measure the passage of the trolley electronically. A handheld stopwatch depends on human reaction time when starting and stopping the timer.

This can introduce additional measurement variation and potentially systematic differences.

Before combining the datasets, the student should establish:

• Which group collected each measurement.
• Which timing method was used.
• The resolution of each instrument.
• The experimental conditions used by each group.
• Whether the measurements were collected over identical distances.
• Whether the methods introduce significant differences in measurement accuracy.

The logbook should preserve the two original datasets separately and document any decision to combine them.

If the methods are not sufficiently comparable, the groups’ results should be analysed separately or their limitations explicitly considered.

Using the same units does not automatically make two datasets equivalent. The measurement process matters just as much as the numbers it produces.

Question 4

A student investigates the effect of temperature on reaction rate.

The original method specifies that the acid concentration must remain constant at 0.10 mol L⁻¹.

After collecting measurements at two temperatures, the student increases the acid concentration to 0.20 mol L⁻¹ because the reaction is taking too long.

They continue collecting results and put every measurement on the same graph, claiming that temperature is the only variable affecting reaction rate.

Explain what is wrong with this approach and how the student should document the change.

Solution 4

The student has changed a controlled variable, so the later measurements cannot automatically be compared with the original results as though only temperature changed.

Acid concentration can also affect reaction rate.

The student must record the original and revised concentrations, the date of the change, the reason for it, and exactly which trials were conducted under each condition.

The student should then separate the original and modified datasets.

The original measurements were collected using 0.10 mol L⁻¹ acid. The later measurements used 0.20 mol L⁻¹ acid.

Combining both sets into one graph without identifying the change creates a problem with experimental validity. A difference in reaction rate could be due to temperature, concentration, or both.

The better approach is to return to one fixed concentration and repeat the relevant measurements across the temperature range.

Alternatively, the student could design a new investigation that deliberately tests both temperature and concentration, but that requires a revised experimental plan.

The tempting approach is to treat the concentration change as a minor adjustment. It is not minor because it affects the very variable being measured.

Question 5

Your group has completed a Chemistry investigation, but you discover that nobody made a logbook entry during the first afternoon of data collection.

You have four pieces of evidence:

• An original sensor CSV file containing 12 measurements and accurate timestamps.
• A photograph taken 18 minutes after the first measurement, showing the water bath display at 40.0°C.
• A teammate who remembers that the first four measurements were collected at 30.0°C before the bath was adjusted.
• A draft spreadsheet that labels all 12 measurements as having been collected at 40.0°C.

The CSV file does not contain temperature information, and there is no independent record of when the water bath was adjusted.

You now need to submit your logbook and analyse the temperature dependence of the results.

What should you record, which evidence can you trust, and can you legitimately classify all 12 measurements as 40.0°C?

Solution 5

No. You cannot legitimately classify all 12 measurements as having been collected at 40.0°C.

The central problem is that the available evidence establishes different things, and none of it independently confirms the temperature associated with every measurement.

Consider each source separately.

Step 1: Preserve the original sensor file.

The CSV file is valuable primary data.

Its timestamps and measurements should remain unchanged. Record its original filename, storage location, and the information available in its metadata.

It provides evidence of when the measurements were recorded and what the sensor measured.

However, because it does not record water-bath temperature, it cannot establish the temperature conditions for each measurement.

Step 2: Record what the photograph actually establishes.

The photograph shows a water bath displaying 40.0°C at the time the photograph was taken.

This is evidence that the bath was at that temperature at that particular time.

It does not establish that the bath was at 40.0°C during the first four measurements.

Nor does it automatically establish that the temperature remained constant throughout the remaining measurements.

Step 3: Preserve your teammate’s recollection as a separate source.

The teammate’s recollection is relevant evidence, but it is not equivalent to a contemporaneous instrument record.

Record the recollection, who provided it, when it was provided, and exactly what they remember.

Do not silently convert that recollection into a verified measurement.

Step 4: Investigate the draft spreadsheet’s origin.

The spreadsheet labels all 12 measurements as 40.0°C, but you need to establish where that information came from.

Was the temperature copied from the final photograph? Was it entered manually? Was it based on an earlier measurement?

Without supporting evidence, the spreadsheet label does not independently establish the temperature of every trial.

Step 5: Make a dated retrospective entry.

You must not backdate an entry or pretend that you recorded something during the original experiment when you did not.

Instead, create a new entry using the actual date of reconstruction.

Clearly identify it as a retrospective account.

Separate the information into:

• Verified information from the original sensor file.
• Information established by the timestamped photograph.
• Information recalled by your teammate.
• Information that remains unknown.

Preserve the original files and identify every source used to reconstruct the investigation.

Step 6: Reconsider which measurements can be compared.

This is the most important scientific decision.

The photograph establishes a temperature at one moment, but the missing record prevents you from establishing the temperature conditions for the entire measurement sequence.

The first four measurements might have been collected at 30.0°C, as your teammate remembers. However, you cannot treat that recollection as independently verified.

Similarly, you cannot assume that every subsequent measurement was collected at 40.0°C without evidence that the bath had reached and maintained that temperature.

If the exact conditions cannot be reconstructed, the affected measurements should be identified as having uncertain experimental conditions.

You may need to repeat the investigation to obtain a defensible dataset. If repetition is impossible, explain the limitation and avoid making a conclusion that the evidence cannot support.

Why this is a difficult logbook problem:

It is tempting to assume that because you have the original measurements and a photograph of the final apparatus, you can reconstruct the experiment completely.

But a record of the measurements is not necessarily a record of the conditions under which they were obtained.

The difference matters. You can preserve the original data perfectly and still be unable to establish whether those measurements are comparable.

A scientifically honest logbook makes that limitation visible rather than hiding it.

08What your logbook should help you do next

A strong logbook gives you something more valuable than a neat collection of laboratory notes: it gives you an evidence trail that you can defend.

When you move on to analysing results, evaluating reliability, and discussing experimental validity, you can trace each conclusion back to the measurements and decisions that produced it.

This is also the connection to Working Scientifically in HSC Physics and Chemistry.

Your final report should be built from that evidence, not the other way around.

The next time you conduct an investigation, record the measurement, the conditions, and the decision while they’re still in front of you. Reconstructing an experiment from memory is much harder than documenting it properly the first time.