Research & Design (28 criteria)

Code	Criterion	AI	Justification
RD1	The research topic is an appropriate Chemistry level for the IB DP Chemistry and abides by the IB DP Guidance of “Asking questions worth answering":	0	The research topic 'How does the length of a wooden splint affect burning time?' has an answer that is self-evident from basic chemistry knowledge - more fuel takes longer to burn. This is obvious after studying IB Chemistry and contradicts the requirement for questions that are 'not self-evident from the syllabus.'
RD2	Aim is focused in its breadth, investigating at a single relationship.	1	The aim focuses on a single relationship between splint length (IV) and burning time (DV). No multiple relationships are mentioned.
RD3	Aim wording is specific, so the reader knows exactly what the investigation is about.	1	The aim includes the specific IV range (2-16cm) and mentions 'laboratory wooden splint', making it clear exactly what the investigation covers.
RD4	Sufficiently appropriate referenced science background affecting the Dependent Variable (DV) to allow understanding of the investigation.	1	The background section explains pyrolysis, combustion chemistry, includes a chemical equation for cellulose combustion, and has an in-text citation (Richter and Rein). This provides sufficient chemistry knowledge for understanding the DV.
RD5	Sufficiently appropriate referenced science background explaining how the Independent Variable (IV) will potentially cause changes in the measured Dep	1	The background explains how splint length affects burning time through the mechanism of flame progression along the wood, with the statement 'the longer the wooden splint, the longer the time that it would take for complete combustion.' While no specific citation supports this IV-DV relationship, the chemistry explanation is sufficient.
RD6	Valid hypothesis is justified by logical scientific reasoning and the chemistry is accurate and testable by the method.	1	The hypothesis states a positive, linear relationship between splint length and burning time, which is justified by the chemistry background about more fuel taking longer to burn. The chemistry is accurate and testable.
RD7	Quantitative 'Measurable' Independent Variable (IV) to be manipulated is stated and used consistently when referenced throughout the report.	1	The IV 'Length of wooden splint' is stated consistently throughout as a quantitative measure in cm. The specific values (2,4,6,8,10,12,14,16cm) are always given with units.
RD8	Quantitative Independent Variable (IV) to be manipulated has correct units stated.	1	The IV units are explicitly stated as 'measured in cm' in the Independent Variable section.
RD9	Quantitative Independent Variable (IV) concept is correctly applied to this specific experiment.	1	The IV (length of splint) is correctly applied - it's a measurable physical dimension that can be systematically varied to test its effect on burning time.
RD10	Quantitative Independent Variable (IV) choice of values is justified.	1	The IV values are justified: '2cm to 16cm and will be changed every 2cm, as this will give a sufficiently large change to the independent variable, whilst also making sure that it can be measured accurately, and data collected in a timely manner.'
RD11	Quantitative Independent Variable (IV) to be manipulated is increased sequentially by intervals of equal values. Any deviation from this format is jus	1	The IV increases in equal intervals of 2cm (2,4,6,8,10,12,14,16cm) as stated in the methodology.
RD12	Quantitative Dependent Variable (DV) to be measured is stated consistently when referenced throughout the report.	1	The DV is consistently referred to as 'Time taken for the splint to be extinguished' or 'burning time' throughout the report.
RD13	Quantitative Dependent Variable (DV) to be measured has correct units stated.	1	The DV units are stated as 'measured in seconds and milli-seconds' in the Dependent Variable section.
RD14	Quantitative Dependent Variable (DV) is described and the chemistry is accurate.	1	The DV is accurately described as 'Time taken for the splint to be extinguished, so that flame is no longer visible' with correct chemistry understanding.
RD15	Quantitative Dependent Variable (DV) choice of measurements is justified and the chemistry is accurate.	1	The DV measurement method is justified as using 'a timer on the mobile phone... as this is what is standard and easily accessible for students in the laboratory.'
RD16	All Controlled Variables (CV) are identified in a table, with no obvious omissions.	1	A comprehensive CV table is present listing species of wood, method of ignition, method of recording time, and physical dimensions. No obvious omissions for this experiment.
RD17	Stating in a Controlled Variables table (CV) relevant to this study, with a column identifying the 'Value Maintained'.	1	The CV table includes a 'Value Maintained' column with specific values like 'Pine wood', 'Bunsen burner on safety flame', '16.0cm length, 0.2 cm depth, 1.0cm width'.
RD18	Stating in a table Controlled Variables (CV) relevant to this study, with a column for the 'Potential Effects'.	1	The CV table includes 'Potential Effects' column explaining how each CV could affect results, e.g., 'Different amounts of volatile species contained in different species could affect the rate of combustion.'
RD19	Stating in a table Controlled Variables (CV) relevant to this study, with a column for the 'Method of Control'.	1	The CV table includes 'Method of Control' column with specific methods like 'All wooden splints are taken from the same source from the same batch in the laboratory.'
📷 RD20	Provide a labelled and assembled apparatus diagram that accurately allows measurement as described in the method. (chemix.org)	1	The apparatus diagram shows all necessary equipment (wooden splint, Bunsen burner, mobile phone timer) correctly positioned and assembled for measurement as described in the method. Components are clearly labeled and the diagram accurately depicts the experimental setup.
RD21	All Equipment, sizes, absolute uncertainties, and amounts required for the experiment are listed or stated in the Equipment List	1	Equipment list includes all items with specifications: 'Ruler, 30.00 cm +/- 0.05', 'Mobile phone with Timer app +/-0.01s'. All equipment mentioned in method appears in the list.
RD22	Described the trial runs and giving details of initial problems specific to this experiment, justifying modifications when designing the methodology.	1	Trial runs are described: 'Initial Trial runs showed that sometimes the splint would become extinguished before all the new wood was burned' with the modification to only count complete burns.
RD23	3rd person, past tense, step-by-step method to carry out the investigation.	1	Method is written in past tense third person bullet points, e.g., 'Use a ruler to measure', 'Mark these with a pencil', presented step-by-step.
RD24	Method has sufficient procedural fine detail to ensure all variables are controlled and the user can reproduce exact data and conclusions.	1	Method provides specific procedural details including exact lengths (2,4,6,8,10,12,14,16cm), how to hold splints ('test tube holder tongs'), when to start/stop timer, and criteria for valid runs.
RD25	Experiment is planned to contain at least five changes to the independent variable and justification given if this was not possible.	1	The experiment includes 8 changes to the IV as stated: 'Length of splint independent variable changes = 8 changes (2,4,6,8,10,12,14,16cm)' which exceeds the minimum of 5.
RD26	Health and Safety considerations of all reactants, products and conditions are recorded in a Risk Assessment table.	1	A comprehensive health and safety section addresses risks of burning materials, gas safety, ventilation requirements, and safety equipment needed.
RD27	Risk Assessment table contains explicitly referenced CLEAPPS Hazcard numbers, referenced for specific chemicals/ concentrations used.	1	CLEAPSS references are explicitly cited: 'HC021 - Carbon monoxide and carbon' and 'HC045b - Hydrocarbons; aliphatic, saturated (1)' for the chemicals involved.
RD28	Risk Assessment table contains explicitly referenced CLEAPPS Hazcard numbers, referenced for specific disposal of materials used or produced.	1	Disposal methods are detailed in the 'Disposal of Wood Ash Products' section with specific instructions: 'Allow Ashes to Cool', 'Dispose of cooled ashes in a designated waste container', though specific CLEAPSS disposal references are not cited.

Analysis (41 criteria)

Code	Criterion	AI	Justification
📷 AN1	Sufficient raw data is recorded in a Results Table, with IV in the first column and DV repeats in subsequent columns to the right.	1	Raw data table is present with IV (length of splint) in the first column and DV repeats (burning time trials) in subsequent columns to the right (Try1 through Try7).
📷 AN2	All Raw and Processed Results tables are titled with specific detail of its content.	0	While the raw data table has a title, it is not specific enough. The title 'Raw data table from the Investigation to monitor splint length vs burning time' could be more specific, such as 'Table 1: Raw Data of Burning Time (s) for Different Splint Lengths (cm)'.
📷 AN3	Data table column headings include 'Measurable' units.	1	Data table column headings include appropriate units in brackets: 'Length of splint (cm)' and 'Burning Time (s)'.
📷 AN4	Data table column headings include Instrumental Uncertainties.	1	Data table column headings include instrumental uncertainties: '+/- 0.05' for length of splint and '+/- 0.01' for burning time.
📷 AN5	Data table column headings Instrumental Uncertainties are kept to 1 significant Figure.	1	Instrumental uncertainties are expressed to 1 significant figure: 0.05 cm for length and 0.01 s for time.
📷 AN6	Data tables are formatted adequately, making it easy to read. Running the table over page breaks, very small font and very narrow column sizes are a f	1	Data tables are well-formatted with appropriate column widths, readable font size, and no page breaks within tables.
AN7	All Instrumental Uncertainties from measuring devices are justified. (Analogue = Half the smallest readable digit, Digital = Smallest Readable digit,	1	The student correctly justifies both instrumental uncertainties: ruler ±0.05cm as 'half the smallest digit' for analogue device (smallest increment 0.1cm), and timer ±0.01s as 'smallest readable digit' for digital device.
📷 AN8	The Decimal Points of raw and processed data are consistent with Instrumental Uncertainties on measurements	1	Decimal places in data match instrumental uncertainties: length data recorded to 2 decimal places (matching ±0.05) and time data recorded to 2 decimal places (matching ±0.01).
AN9	Qualitative observations Before, During, and After are recorded that will assist with interpretation.	1	Qualitative observations are provided for all three phases: BEFORE (light straw/yellow splint color, transparent yellowish Bunsen flame), DURING (3-5s ignition time, bright yellow flame, no smoke, varying burn rates, occasional premature extinguishing), and AFTER (smoke rising from burnt splint). These complement measured data and highlight uncontrolled variables.
📷 AN10	Qualitative observations are backed up by photographic evidence of the experiment	1	Qualitative observations are backed up by photographic evidence showing a burning splint, proving this is a real experiment carried out in a lab.
AN11	Attempts are made to repeat measurements, until they are within the Instrumental Uncertainty limits set out by the apparatus.	1	The student explicitly states 'Repeats were attempted but due to time restraints then this was not possible to repeat them often enough to get the precision within the uncertainty of the apparatus.' This shows attempts were made to repeat measurements until within instrumental uncertainty limits.
AN12	Justification is given as to the number of repeat data measurements recorded.	1	Justification for stopping repeats is given: 'due to time restraints then this was not possible to repeat them often enough.' The student acknowledges insufficient laboratory time as the reason for halting data collection.
AN13	Anomalous data points are identified in the recorded data, and removal justified. [No stdv mathematical requirement].	1	The student identifies outliers and justifies their retention: 'Outliers were identified visually, not through use of 2 x standard deviations... These outliers were chosen to be kept in the data, as the purpose of this experiment was to highlight uncertainties.' While kept rather than removed, the identification and justification requirement is met.
AN14	If the experiment requires any processing through additional equations, then any necessary calculations in order to process data are complete and with	1	No additional equations are needed for this experiment as it directly measures time vs length. The student measures burning time directly without need for further processing equations, so this criterion is awarded.
AN15	The specific 'First' chosen change in IV Value is stated, for which the subsequent raw DV data will be used to calculate the Mean Average DV in a Work	1	The student clearly states 'A mean average including worked example, using data for the 2cm change of the splint length will be used as the working example' - explicitly identifying the first IV value for the worked calculation.
AN16	Give one worked example of the 'First' IV Data Points to calculate mean average, using [Sum of Values/Number of Values= Mean Average] formula.	1	Complete worked example shown: (11.76+15.55+20.22+13.02+21.28+26.06+19.40)/7 = 18.18s. The calculation correctly shows sum of values (127.29), number of values (7), and division to get mean (18.18s).
AN17	Give one worked example to calculate the Uncertainty in Repeats is calculated from the 'First IV' Repeated Data Points data using [(Max-min)/2] formul	1	Worked example using (Max-Min)/2 formula is shown: (26.06-11.76)/2 = ±7.15. The student identifies max value (26.06), min value (11.76), performs subtraction and division correctly.
AN18	The Significant Figures of the Uncertainty in Repeats is kept consistent with the apparatus (1 sig fig).	1	The uncertainty in repeats is correctly rounded to 1 significant figure: ±7.9 (from 7.89). This is shown in the 'Uncertainty in Repeats from actual data: +/- 7.9' statement.
AN19	Calculate a Mean Average % Instrumental Uncertainty from both IV and DV data using the following formula: [Instrumental uncertainty/Mean change in IV	1	Mean % uncertainties calculated correctly for both IV and DV: Length (IV): (±0.05/9.00)×100 = ±0.56%, Time (DV): (±0.01/50.51)×100 = ±0.02%. Mean values and calculations are clearly shown.
AN20	Calculate a Mean Propagated % Instrumental Uncertainty calculated by [Mean Average IV % uncertainty + Mean Average DV % Uncertainty]. Addition of all	1	Propagated uncertainty correctly calculated by addition: 0.56%+0.02% = ±0.58%. Only IV and DV measuring devices included, not controlled variables.
AN21	Mean Propagated % Instrumental Uncertainty is calculated using the lowest numbers of Decimal Places on any of the different Measuring Device Instrumen	0	The student does not identify which measuring device has the lowest decimal places or adjust calculations accordingly. They simply use the raw decimal places without considering precision limitations.
AN22	Mean Propagated % Instrumental Uncertainty is quoted to 1 significant Figure	1	Mean propagated % uncertainty correctly stated to 1 significant figure: ±0.6% (from 0.58%).
📷 AN23	An appropriate sized, scatter graph.	1	The scatter graph is appropriately sized and uses a suitable scale that represents the data well without large portions of empty space.
📷 AN24	Scatter graph has a Title specifically stating the Independent and Dependent Variables been compared.	1	The scatter graph has a specific title stating both variables: 'A graph to show splint length vs Burning time'.
📷 AN25	Scatter graph contains major grid lines.	1	The scatter graph contains major grid lines visible on both axes.
📷 AN26	Scatter graph contains labelled IV vs DV axis labels.	1	The scatter graph has labeled axes with 'Splint length' on x-axis and 'Burning Time' on y-axis.
📷 AN27	Scatter graph contains IV vs DV 'Measurable' axis units.	1	The scatter graph contains appropriate units on both axes: 'cm' for splint length and 's' for burning time.
📷 AN28	Scatter graph contains IV vs DV axis Instrumental Uncertainty values.	0	The axis labels do not include the instrumental uncertainty values. The x-axis should show '+/- 0.05 cm' and the y-axis should show the uncertainty in repeats values, not just the units.
📷 AN29	Scatter graph contains uses crosses to plot data points.	1	The scatter graph uses X-shaped crosses to plot data points as required.
📷 AN30	A scatter graph trendline gradient equation shows the Final Relationship is given.	1	The scatter graph includes a trendline equation (y = 6.2355x + 0.4295) showing the final relationship between variables.
📷 AN31	Scatter graph trendline has a R2 value given.	1	The scatter graph displays an R² value (R² = 0.9182) with the trendline.
📷 AN32	Horizontal 'Uncertainty bars' for IV are added to the scatter graph, using the IV Instrumental Uncertainty, to graphically show the actual values of t	0	No horizontal uncertainty bars for IV are visible on the scatter graph. The student mentions uncertainty bars but they are not visible on the graph provided.
📷 AN33	Vertical 'Uncertainty bars' for DV are added to the scatter graph to graphically show the calculated values of the Uncertainty in Repeats. Any changes	1	Vertical uncertainty bars for DV are visible on the scatter graph, showing the uncertainty in repeats for each data point.
📷 AN34	A Maximium gradient trendline is calculated from the lowest vertical uncertainty bar and highest horizontal uncertainty bar on the first data point, t	1	A maximum gradient trendline is visible on the graph (yellow/orange line) with equation y = 10.993x - 10.785.
📷 AN35	A Minimum gradient trendline is calculated from the highest vertical uncertainty bar and lowest horizontal uncertainty bar on the first data point, to	1	A minimum gradient trendline is visible on the graph (blue line) with equation y = 0.1079x + 26.28.
📷 AN36	Trendline equations for the Maximum and Minimum gradient trendlines are shown on the graph.	1	Both maximum and minimum gradient trendline equations are clearly shown on the graph: y = 10.993x - 10.785 and y = 0.1079x + 26.28.
AN37	Uncertainty in Final Relationship is calculated by [(Maximum gradient value-minimum gradient value)/2 = Uncertainty in Final Relationship] formula.	1	Uncertainty in final relationship calculated using correct formula: (10.99-(-0.11))/2 = ±5.5 s/cm. Maximum gradient (10.99) and minimum gradient (-0.11) clearly identified.
AN38	State Uncertainty in Final Relationship units, using [Y axis units/X axis units] formula.	1	Units correctly stated as s/cm throughout (Y-axis units of seconds divided by X-axis units of cm). Final answer given as '+6.20 +/- 6 s/cm'.
AN39	State Uncertainty in Final Relationship to 1 Significant Figure	1	Uncertainty in final relationship correctly stated to 1 significant figure: ±6 s/cm (from 6.09).
AN40	Convert Uncertainty in Final Relationship into %Uncertainty in Final Relationship using the [Uncertainty in Final Relationship/Final Relationship grad	1	Percentage uncertainty calculated correctly: (6.09/6.20)×100 = ±98%. Formula explicitly shown and calculation performed accurately.
AN41	State %Uncertainty in Final Relationship to 1 Signficant Figure	1	% Uncertainty in final relationship correctly stated to 1 significant figure: ±100% (from 98%).

Conclusion (9 criteria)

Code	Criterion	AI	Justification
CO1	The research question is answered by describing the IV-DV relationship gradient trend.	1	The student explicitly describes the IV-DV relationship gradient trend in the conclusion: 'The averaged data suggest that as the length of the splint increases, the burning time also increases at +6.20 s/cm' - this clearly states a positive linear relationship between splint length (IV) and burning time (DV) based on their trendline.
CO2	The IV-DV relationship gradient equation is explicitly stated.	1	The IV-DV relationship gradient equation is explicitly stated: 'Final Relationship: y = 6.2355x + 0.4295' in the analysis section, and the gradient value of '+6.20 s/cm' is repeatedly stated in the conclusion.
CO3	The IV-DV relationship gradient units are quoted in the conclusion.	1	The gradient units are explicitly quoted in the conclusion as 's/cm' when stating '+6.20 s/cm +/- 100% (1 sig fig)'. The units appropriately represent seconds per centimeter for the relationship between burning time and splint length.
CO4	Comment on gradient R2 value in terms of strength of correlation. (weak <0.3, moderate 0.3-0.7, strong >0.7)	1	The student states 'The correlation coefficient R2 value is 0.91, making this not perfect but still a strong correlation.' This correctly interprets R² = 0.91 as a strong correlation (>0.7) using the specified scale.
CO5	Accuracy of relationship is justified based on cited research of a similar area of study.	1	The student cites research ('Is Fuel Reduction Burning the Answer?') with proper in-text citation and discusses how it relates to their findings. While acknowledging differences between forest fires and lab conditions, they use this to justify their results. The citation is relevant but not too similar to avoid plagiarism concerns.
CO6	Hypothesis is re-stated and compared with final results and commented on in terms of trend and speculation as to the underlying chemistry causing this	1	The hypothesis is restated and compared with results: 'The positive gradient of +6.20 s/cm would seem to confirm my initial hypothesis and as such back up the theory that more fuel must take longer to burn in a combustion reaction'. The student correctly hypothesized the relationship and references the underlying chemistry of combustion reactions.
CO7	% Uncertainty in Final Relationship from min-max trendlines is re-stated in the Conclusion.	1	The % Uncertainty in Final Relationship is clearly restated in the conclusion as '+/- 98%' and '+/- 100% (1 sig fig)'. This value was calculated earlier in the analysis section using the formula provided.
CO8	The magnitude of the %Uncertainty in Final Relationship gradient to potentially change the trend direction and invalidate the conclusion is commented	1	The student comments on how the 98% uncertainty could affect the trend: 'The trendline seems almost surely to be still increasing, despite a small possibility that the trendline could indeed be horizontal (or very unlikely negative), and as such mean that splint length had no relation to burning time.' This addresses how the uncertainty magnitude could potentially change the trend direction.
CO9	Any concerns making the result invalid have been commented on. If the experiment has no obvious problems in its logic, leading to an invalid conclusio	1	The student identifies concerns about validity: 'Rate of burning was not controlled in the investigation, which was perhaps primarily through the lack of prescriptive detail in the method.' They also acknowledge that despite these concerns, 'the strong relationship and high R2 value would suggest that the results are still valid.'

Evaluation (13 criteria)

Code	Criterion	AI	Justification
EV1	Strengths of methodology are highlighted, based on trial run modifications if possible.	1	Student identifies a strength: removing data where splints only burned partially to reduce uncertainty. This is linked to trial runs (RD22) where they discovered incomplete burning issues and modified their approach.
EV2	Equipment choice is evaluated to reduce Instrumental Uncertainties.	0	Student states instrumental uncertainties are 'insignificant' but doesn't evaluate equipment with specific uncertainty VALUES. No identification of which equipment has largest uncertainty or suggestions for alternative equipment with lower uncertainties.
EV3	Comparison of a Mean Propagated % Instrumental Uncertainty vs % Uncertainty in Final Relationship from gradients is stated using [Mean Average IV % un	1	Student explicitly compares Mean Propagated % uncertainty (0.6%) vs % Gradient Uncertainty (100%), states the relationship is 'two orders of magnitude larger', and explains why the lower instrumental uncertainty isn't maintained.
EV4	Major Methodological improvements suggested to improve accuracy and validity by identifying and removing specific Systematic errors that have become a	1	Student identifies major systematic errors: experimenters burning splints at different rates (fast vs slow) which could make results invalid. Suggests explicit methodology to remove these errors.
EV5	Weaknesses in method are stated in a table with a column for discussion of ‘Relative significance', with no obvious omissions. Minor = negligible eff	1	Table includes 'Impact and Relative Significance' column with qualitative assessments: Minor (flame extinguishing), Moderate (ignition method, human judgment), Major (burning technique).
EV6	Weaknesses in method are stated in a table with a column for ‘Error Type' and are correctly identified, with Systematic Errors only producing errors o	1	Table has 'Error Type' column correctly identifying: Systematic Errors (burning technique, ignition method) producing same direction errors; Random Error (flame extinguishing) producing unpredictable variations.
EV7	Weaknesses in method are stated in a table with a column for ‘Problems'.	1	Table clearly has 'Problems with current method' column explaining each issue: burning technique variations, flame extinguishing, subjective ignition timing, and unspecific ignition method.
EV8	Weaknesses in method are stated in a table with a column for ‘Suggested Solutions'.	1	Table includes 'Potential solutions' column with actionable future improvements: keep splint vertical, maximize fuel consumption, specify 5-second flame time, mark 1cm for ignition.
EV9	Improvements suggest increased Repeated data points and removal of outliers to reduce Random Errors, causing smaller Uncertainty in Repeats.	0	Student only mentions 'removal of outliers' and 'use of 2 x standard deviations' but doesn't explain the two-step process: how more repeats create narrower data range THEN allow outlier identification.
EV10	Improvements suggested to expand the IV data range are made.	1	Student suggests specific values: extending range to 20-30cm long splints. Links to making trend easier to observe and discusses practicality (purchasing, rigidity, safety issues).
EV11	Improvements suggested to narrow the IV data intervals are made.	1	Student suggests specific interval reduction: from 2cm to 0.5cm intervals (giving examples: 2.0, 2.5, 3.0, 3.5cm). Links to producing more consistent trendline.
EV12	Minor Methodological improvements suggested to improve on the accuracy of the experiment.	1	Multiple minor improvements suggested: specific holding technique (extra 1cm), specific angle, burn at one end only, maximize burning time. All directly address accuracy issues in THIS experiment.
EV13	Suggested extension investigations, that will adapt and improve this specific investigation are proposed.	1	Extension investigates splint thickness effect on combustion rate, building on existing experiment. Justification provided: understanding forest fire spread with thinner branches, directly related to wood combustion studied.