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 question 'How does the length of a laboratory wooden splint affect the time it takes to burn completely?' fails RD1 criteria. This is a basic relationship that can be easily answered through online searches, is commonly found in combustion textbooks, and the answer is self-evident from basic chemistry principles - more fuel takes longer to burn. The topic lacks the depth and originality required for IB DP level investigation.
RD2	Aim is focused in its breadth, investigating at a single relationship.	1	The aim focuses on a single relationship between length of wooden splint (IV) and time to burn completely (DV). The independent variable is clearly defined as splint length (2-16cm) and the dependent variable is burning time measured in seconds. The aim is appropriately focused and does not investigate multiple relationships or broader scopes. The single chemical relationship being investigated is well-defined and isolated.
RD3	Aim wording is specific, so the reader knows exactly what the investigation is about.	1	The aim clearly states the specific investigation scope: wooden splint length (2-16cm range) affecting complete burning time. It includes the specific IV range, uses precise terminology ('laboratory wooden splint', 'burn completely'), and allows readers to understand exactly what is being studied. While it could specify the wood type or controlled variables like temperature, the aim meets the criterion's requirements for specificity and clarity about the investigation's purpose.
RD4	Sufficiently appropriate referenced science background affecting the Dependent Variable (DV) to allow understanding of the investigation.	0	The background section lacks sufficient depth to allow reader understanding without additional literature. While pyrolysis and combustion are mentioned with one chemical equation, the explanation is superficial. The dependent variable (burning time) lacks scientific grounding - no discussion of combustion kinetics, heat transfer mechanisms, or factors affecting burn rates. Only two citations provided, with minimal integration into explanations. Reader cannot understand the chemical basis of time-dependent burning from this background alone.
RD5	Sufficiently appropriate referenced science background explaining how the Independent Variable (IV) will potentially cause changes in the measured Dep	0	While the student identifies the independent variable (splint length) and provides a logical explanation of how longer splints would take more time to burn completely, the RD5 section lacks any in-text citation supporting this relationship. The explanation is scientifically sound but fails to meet the requirement for referenced support linking the IV to the DV. Citations appear elsewhere but not specifically supporting the IV-DV relationship in RD5.
RD6	Valid hypothesis is justified by logical scientific reasoning and the chemistry is accurate and testable by the method.	1	The hypothesis is explicitly stated and predicts a positive, linear relationship between splint length and burning time. It's logically derived from the background explanation that longer splints contain more fuel and must burn sequentially from one end. The chemistry reasoning is accurate - more cellulose fuel requires more time for complete combustion. The hypothesis is testable by the proposed method of measuring burn times for different lengths.
RD7	Quantitative 'Measurable' Independent Variable (IV) to be manipulated is stated and used consistently when referenced throughout the report.	0	The IV is not consistently referenced with quantitative values throughout. While clearly defined as 'Length of wooden splint, measured in cm' in RD7 with specific values (2-16cm), later references often drop the quantitative aspect. In methodology step 1, it mentions 'specified lengths' and lists values, but step 4 refers to 'shortest splint' without the cm value. The criterion requires quantitative values to always be present when the IV is referenced.
RD8	Quantitative Independent Variable (IV) to be manipulated has correct units stated.	1	The student clearly states the quantitative independent variable as 'Length of wooden splint, measured in cm' in the dedicated IV section. The units (cm) are explicitly stated and scientifically appropriate for length measurements. The variable and units are mentioned directly together in the first description of the independent variable, fulfilling the criterion requirements.
RD9	Quantitative Independent Variable (IV) concept is correctly applied to this specific experiment.	1	The student correctly identifies the quantitative IV as 'Length of wooden splint, measured in cm, using a ruler' with specific range (2-16cm) and intervals (every 2cm). Units are clearly stated, systematic manipulation is described, and the IV is directly linked to the research question and expected outcomes in the dependent variable (burning time). The description adequately addresses all required elements of the criterion.
RD10	Quantitative Independent Variable (IV) choice of values is justified.	1	The student provides clear justification for their IV values (2-16cm, 2cm intervals). They explain the range ensures sufficient change while maintaining accurate measurement, that 1mm increments would be difficult to measure/cut, and that 8 data points will enable valid conclusions from graphing. The justification links directly to experimental objectives and demonstrates logical reasoning based on practical measurement limitations and data analysis needs.
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 student clearly specifies a quantitative independent variable (length of wooden splint) that is manipulated in equal increments of 2cm throughout the experiment (2, 4, 6, 8, 10, 12, 14, 16cm). The report explicitly states the interval size and provides justification for choosing 2cm increments, explaining that smaller changes would be difficult to measure accurately and larger changes would reduce data points. The criterion is met with appropriate reasoning.
RD12	Quantitative Dependent Variable (DV) to be measured is stated consistently when referenced throughout the report.	0	The DV is inconsistently referenced throughout the report. Initially stated as 'Time taken for the splint to be extinguished' in RD12, but later referenced as 'burning time' (multiple instances), 'time of burning' (AN27), and 'burning time of the splint' (RD6). These variations create ambiguity. To score 1, use the exact same term 'Time taken for the splint to be extinguished' consistently throughout all references to the dependent variable.
RD13	Quantitative Dependent Variable (DV) to be measured has correct units stated.	1	The quantitative dependent variable is clearly identified as 'Time taken for the splint to be extinguished' and the correct units are explicitly stated as 'measured in seconds and milli-seconds'. The units appear consistently throughout the report in data analysis sections. While there are minor formatting variations, the essential requirement of stating appropriate units (seconds) for the time measurement is clearly met.
RD14	Quantitative Dependent Variable (DV) is described and the chemistry is accurate.	0	The DV description lacks essential detail required by RD14. While it identifies 'time for splint to be extinguished' measured in seconds, it fails to explain HOW this is quantitatively assessed beyond mentioning a phone timer. Missing: detailed measurement procedure, precision considerations, definition of exact endpoint criteria, and connection to combustion chemistry. The description is too superficial for the quantitative rigor expected.
RD15	Quantitative Dependent Variable (DV) choice of measurements is justified and the chemistry is accurate.	0	The student identifies time as the DV but provides no scientific justification for WHY this measurement method was chosen to achieve the experimental objective. The statement 'measured in seconds and milli-seconds, as this is what is standard and easily accessible' only explains convenience, not scientific rationale. Missing is explanation of how time measurement relates to combustion kinetics or why this approach best measures the chemical process being investigated.
RD16	All Controlled Variables (CV) are identified in a table, with no obvious omissions.	1	The student provides a comprehensive table of Controlled Variables with clear identification of each CV (species of wood, method of ignition, method of recording time, physical dimensions), values maintained, potential effects, and control methods. All critical variables for a combustion experiment are included. The table format is appropriate and complete with no obvious omissions. Minor formatting variations do not detract from meeting the criterion requirements.
RD17	Stating in a Controlled Variables table (CV) relevant to this study, with a column identifying the 'Value Maintained'.	1	A comprehensive Controlled Variables table is present with clearly identified variables (wood species, ignition method, recording method, physical dimensions) and specific values maintained for each (Pine wood, Bunsen burner on safety flame, mobile phone timer, specific dimensions). The table includes relevant factors that could affect the study's results. While the format could be cleaner, all required elements are present and the controlled variables are directly pertinent to the burning time investigation.
RD18	Stating in a table Controlled Variables (CV) relevant to this study, with a column for the 'Potential Effects'.	1	The student provides a comprehensive table listing controlled variables with a clear 'Potential Effects' column. Each CV includes specific explanations of how changes would influence the dependent variable (burning time), such as 'Different amounts of volatile species...could affect the rate of combustion' and 'Thicker splints will contain more wood and possibly increase the burning time.' The explanations are scientifically plausible and contextually relevant to the study.
RD19	Stating in a table Controlled Variables (CV) relevant to this study, with a column for the 'Method of Control'.	1	A comprehensive controlled variables table is present with clear columns for 'Controlled Variable', 'Value Maintained', 'Potential Effects', and 'Method of Control'. The table identifies 4 relevant CVs (wood species, ignition method, recording method, and physical dimensions) with specific, feasible control methods. Each CV has detailed descriptions of how it's controlled. The table is well-organized and addresses the criterion requirements effectively.
📷 RD20	Provide a labelled and assembled apparatus diagram that accurately allows measurement as described in the method. (chemix.org)	1	The student provides a clear, labeled apparatus diagram showing all necessary components: Bunsen burner on safety flame, wooden splint, mobile phone timer, and setup on a table. All components are properly labeled and accurately positioned according to the experimental method. The diagram effectively illustrates how the splint will be ignited and timed, allowing for measurement as described in the methodology.
RD21	All Equipment, sizes, absolute uncertainties, and amounts required for the experiment are listed or stated in the Equipment List	0	Equipment list is incomplete and lacks essential details. Missing: exact quantities of materials (number of matches, gas for Bunsen burner), specific scientific names for substances (methane gas), uncertainties for several items (scissors, test tube holder tongs, heatproof mat, Bunsen burner, matches), and sizes/capacities for most equipment. Several apparatus mentioned in methodology (pencil for marking, gas lighter) are not listed in equipment section at all.
RD22	Described the trial runs and giving details of initial problems specific to this experiment, justifying modifications when designing the methodology.	1	RD22 clearly describes initial problems from trial runs: splints becoming extinguished before complete burning, leading to method modification requiring flame to reach the end for valid results. The controlled variables table further details methodological problems (burning technique, flame extinction, subjective ignition timing) with their impacts and solutions. This demonstrates authentic laboratory work with real problem-solving and method refinement.
RD23	3rd person, past tense, step-by-step method to carry out the investigation.	0	The methodology section uses second person ('Use a ruler', 'Mark these', 'Set up a bunsen burner') and imperative mood rather than third person past tense. The method should use pronouns like 'he/she/they' and past tense verbs like 'was measured', 'were cut', 'was ignited'. While the step-by-step format is present, the fundamental voice and tense requirements are not met throughout the methodology section.
RD24	Method has sufficient procedural fine detail to ensure all variables are controlled and the user can reproduce exact data and conclusions.	0	While the method contains 8 numbered steps, it lacks critical procedural details needed for replication. Key missing elements: no specific splint holding position/angle, no precise ignition time (5 seconds mentioned in CV table but not method), no specification of flame distance from splint, no controlled burning angle, and vague timing start/stop criteria. The method is too general and relies on subjective judgment rather than specific, measurable procedures.
RD25	Experiment is planned to contain at least five changes to the independent variable and justification given if this was not possible.	0	The student planned 8 changes to the independent variable (2, 4, 6, 8, 10, 12, 14, 16cm), which exceeds the minimum requirement of 5 changes. This is clearly stated in the methodology section where it explicitly mentions '8 changes' and lists all the specific lengths. Since more than 5 changes were planned, no justification for having fewer changes was needed. The criterion is fully met.
RD26	Health and Safety considerations of all reactants, products and conditions are recorded in a Risk Assessment table.	0	While health and safety considerations are mentioned in a paragraph format under RD26, there is no Risk Assessment table present. The criterion specifically requires a table that comprehensively lists all reactants, products, and experimental conditions with corresponding hazards and safety measures. The student provides general safety information but fails to present it in the required tabular format with specific chemical/condition entries matched to their hazards.
RD27	Risk Assessment table contains explicitly referenced CLEAPPS Hazcard numbers, referenced for specific chemicals/ concentrations used.	0	The Health and Safety section mentions only two CLEAPSS Hazcard numbers (HC021 and HC045b) but lacks explicit connection to specific chemicals and their concentrations used in the experiment. The report does not identify specific chemicals with concentrations (only mentions methane gas supply without concentration), and the Hazcards are not properly linked to the actual materials used. A proper risk assessment table format is missing entirely.
RD28	Risk Assessment table contains explicitly referenced CLEAPPS Hazcard numbers, referenced for specific disposal of materials used or produced.	0	The Risk Assessment section references CLEAPPS Hazcards HC021 and HC045b but does not provide specific disposal methods from these Hazcards for the materials used/produced. While general disposal advice for wood ash is given, it lacks explicit reference to CLEAPPS Hazcard disposal recommendations. The student needs to cite specific disposal methods from the referenced Hazcards for all materials used (wooden splints, ash products, etc.) rather than providing generic disposal guidance.

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	A comprehensive raw data table is present showing the Independent Variable (Length of splint in cm) in the first column and Dependent Variable trials (Try1 through Try7) in subsequent columns to the right. All data entries include proper units (cm for length, seconds for time with ±0.01 precision). The traditional format is followed correctly with IV in the first vertical column and repeated DV measurements in columns to the right.
📷 AN2	All Raw and Processed Results tables are titled with specific detail of its content.	0	None of the data tables in the images have titles. There are multiple tables showing raw data, processed data, uncertainty calculations, and results, but all lack descriptive titles that would indicate their specific content. Every table is presented without any heading to identify what data it contains, which fails to meet the criterion requirement for titled tables with specific detail of content.
📷 AN3	Data table column headings include 'Measurable' units.	0	Multiple data tables lack proper units in column headings. The main results table shows 'Length of splint (cm)' correctly, but 'Burning Time (s)' appears without units in several tables. Additionally, some tables show 'Uncertainty in Repeats' without specifying units (should be seconds). The raw data table shows 'Try1', 'Try2', etc. columns without units. While some headings are correct, the inconsistent and missing units across multiple tables fail to meet the criterion requirements.
📷 AN4	Data table column headings include Instrumental Uncertainties.	0	The data tables show column headings but lack instrumental uncertainties for the raw data measurements. While the equipment list mentions 'Ruler, 30.00 cm +/- 0.05' and 'Mobile phone with Timer app +/-0.01s', these uncertainties are not included in the actual data table column headings for 'Length of splint (cm)' and 'Burning Time (s)'. The raw data table headings must explicitly show the instrumental uncertainties (e.g., ±0.05 cm, ±0.01 s).
📷 AN5	Data table column headings Instrumental Uncertainties are kept to 1 significant Figure.	0	Multiple data tables show instrumental uncertainties expressed with more than 1 significant figure. The ruler uncertainty is shown as '0.05' (2 significant figures) and timer uncertainty as '0.01' (2 significant figures) throughout the tables. According to the criterion, these should be expressed as single significant figures like '0.05' → '0.05' is actually acceptable, but '0.01' should be '0.01'. However, upon closer inspection, both values do follow 1 sig fig rule correctly.
📷 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	0	Multiple data tables have severe formatting issues that significantly impair readability. Several tables use extremely small fonts that are difficult to read. Many tables have very narrow column widths causing data truncation and cramped appearance. Some tables span across what would be page breaks with poor organization. The overall layout makes it challenging to scan and interpret the data effectively, failing to meet basic readability standards.
AN7	All Instrumental Uncertainties from measuring devices are justified. (Analogue = Half the smallest readable digit, Digital = Smallest Readable digit,	1	The student provides clear justifications for both instrumental uncertainties. For the ruler (analog): ±0.05 because smallest increment is 0.1cm and half the smallest digit is recommended for analog devices. For the mobile phone timer (digital): ±0.01s because this is the smallest readable digit on the digital timer. Both justifications correctly apply the analog/digital rules and explain the reasoning behind each uncertainty value.
📷 AN8	The Decimal Points of raw and processed data are consistent with Instrumental Uncertainties on measurements	0	The instrumental uncertainty for time measurement is stated as ±0.01s, requiring data to be reported to 2 decimal places. However, the raw data tables show time measurements reported to various decimal places (11.76, 15.55, 20.22, etc.) which is inconsistent with the 0.01s uncertainty. Additionally, processed data (averages) are reported to 2 decimal places (18.18, 26.63) which is correct, but the inconsistency in raw data decimal places violates the criterion.
AN9	Qualitative observations Before, During, and After are recorded that will assist with interpretation.	0	While qualitative observations are present, they are not clearly organized into Before, During, and After phases as required. The observations are listed as general statements without distinct phase separation. The student mentions initial wood color and flame appearance, burning characteristics, and post-combustion smoke, but these need to be explicitly categorized into the three required phases to meet the criterion standard.
📷 AN10	Qualitative observations are backed up by photographic evidence of the experiment	1	The report includes a clear photograph showing a burning wooden splint with visible flame, which directly supports the experimental observations described in the methodology. The image effectively demonstrates the actual burning process and provides visual evidence that this is a real laboratory experiment involving combustion of wooden splints, meeting the criterion's requirement for photographic evidence backing up qualitative observations.
AN11	Attempts are made to repeat measurements, until they are within the Instrumental Uncertainty limits set out by the apparatus.	1	The student explicitly mentions attempting repeats in AN11: '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.' The methodology also shows multiple trials were conducted (8 changes with repeats). While they acknowledge not achieving instrumental uncertainty limits, the key criterion of 'attempted' repeats is clearly demonstrated.
AN12	Justification is given as to the number of repeat data measurements recorded.	1	The student provides clear justification for halting data collection in AN12: '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 directly addresses the criterion by explaining that laboratory time constraints prevented additional repetitions. While brief, this represents an honest and realistic rationale that IB students commonly face, which the criterion explicitly acknowledges as acceptable.
AN13	Anomalous data points are identified in the recorded data, and removal justified. [No stdv mathematical requirement].	0	The student mentions identifying outliers visually and notes that some data points seemed significantly different, but fails to specifically identify which data points in their dataset are anomalous. They explicitly state outliers were 'chosen to be kept in the data' rather than removed, which contradicts the criterion requirement for removal with justification. No specific anomalous data points are identified or justified for removal.
AN14	If the experiment requires any processing through additional equations, then any necessary calculations in order to process data are complete and with	1	The experiment measures length of wooden splint vs. time to burn completely. This is a direct relationship between two measurable variables requiring no additional equations to process the raw data into the dependent variable. The student directly measures burning time with a timer, so no calculations like enthalpy formulas are needed to derive the dependent variable from raw measurements.
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 in AN15 that they will use data for the 2cm splint length as their worked example, followed immediately by the calculation: (11.76+15.55+20.22+13.02+21.28+26.06+19.40)/7 = 18.18s. The 2cm length corresponds to the first IV value in their data range (2-16cm), making it easily followable for readers. The IV value selection is unambiguous and specific.
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	The student provides a clear worked example in AN14-AN15 using the first IV data points (2cm splint length). They explicitly show: 1) Sum of values: (11.76+15.55+20.22+13.02+21.28+26.06+19.40), 2) Number of values: 7, 3) Division to find mean: /7 = 18.18s. The required formula [Sum of Values/Number of Values = Mean Average] is demonstrated through the calculation structure, meeting the criterion requirements.
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	The student provides a clear worked example in section AN17 using the (Max-min)/2 formula. They identify the maximum value (26.06) and minimum value (11.76) from the 2cm splint data, correctly perform the subtraction (26.06-11.76), divide by 2, and present the final uncertainty value of ±7.15. All mathematical operations are shown and correctly executed, meeting the criterion requirements.
AN18	The Significant Figures of the Uncertainty in Repeats is kept consistent with the apparatus (1 sig fig).	0	The uncertainty in repeats is reported as +/-7.9 (section AN17), which has 2 significant figures, not 1 as required. Later, the student correctly applies 1 sig fig to other uncertainties like +/-6 s/cm and +/-100%, but the initial uncertainty in repeats calculation fails to follow the 1 sig fig rule. This should be +/-8 to meet the criterion.
AN19	Calculate a Mean Average % Instrumental Uncertainty from both IV and DV data using the following formula: [Instrumental uncertainty/Mean change in IV	1	The student correctly calculates percentage instrumental uncertainty for both IV and DV measuring devices. For IV (length): average = 9.00cm, uncertainty ±0.05cm, giving 0.56%. For DV (time): average = 50.51s, uncertainty ±0.01s, giving 0.02%. Both calculations use the proper formula and are clearly presented. The student appropriately excludes controlled variables and focuses only on devices used to produce IV and DV data.
AN20	Calculate a Mean Propagated % Instrumental Uncertainty calculated by [Mean Average IV % uncertainty + Mean Average DV % Uncertainty]. Addition of all	1	The student provides a complete worked example for propagated percentage uncertainty calculation in sections AN27-AN30. They correctly identify and calculate percentage uncertainties for IV (length: 0.56%) and DV (time: 0.02%) measuring devices only, explicitly excluding controlled variable devices. The calculation clearly shows: 0.56% + 0.02% = 0.58% = 0.6% (1 sig fig). All required elements are present: device identification, individual uncertainties, step-by-step addition, and final propagated value.
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 fails to identify which measuring device has the lowest decimal places. They calculate propagated uncertainty using 0.05 (ruler, 2 decimal places) and 0.01 (timer, 2 decimal places) without recognizing they're equal. The calculation should identify that both devices have 2 decimal places, then proceed accordingly. The student also doesn't explicitly reference or justify their choice based on decimal place comparison as required by the criterion.
AN22	Mean Propagated % Instrumental Uncertainty is quoted to 1 significant Figure	1	The student explicitly calculates and presents the Mean Propagated % Instrumental Uncertainty as +/- 0.6% (1 sig fig) in section AN30. The calculation is shown correctly: Length uncertainty 0.56% + Time uncertainty 0.02% = 0.58%, rounded to 0.6% to 1 significant figure. The percentage format is used and the method is clearly explained with worked examples for both length and time measurements.
📷 AN23	An appropriate sized, scatter graph.	0	The scatter graph contains excessive empty space, particularly in the upper right quadrant where data points don't extend. The y-axis scale goes to 200 seconds but the highest data point is only around 105 seconds, creating large portions of unused graph space. This indicates an inappropriate scale has been chosen, making the graph less effective at representing the data variability and failing to meet the criterion requirements.
📷 AN24	Scatter graph has a Title specifically stating the Independent and Dependent Variables been compared.	1	The scatter graph has a clear title 'A graph to show splint length vs Burning time' which explicitly states both the independent variable (splint length) and dependent variable (burning time). The title is positioned prominently at the top of the graph and directly relates to the graph's content, meeting the criterion requirements.
📷 AN25	Scatter graph contains major grid lines.	1	The scatter graph clearly shows major grid lines on both x and y axes. These are prominent, continuous lines that intersect at regular intervals forming a visible grid pattern across the plotting area. The grid lines are clearly distinguishable and allow readers to easily relate data points to the results tables shown in previous images.
📷 AN26	Scatter graph contains labelled IV vs DV axis labels.	1	The scatter graph clearly shows labeled axes with the independent variable (Splint length +/- 0.05 (cm)) on the horizontal axis and dependent variable (Burning Time +/- 0.01s) on the vertical axis. Both labels are specific to the variables studied and include appropriate units of measurement (cm and seconds). The axis labels meet the criterion requirements.
📷 AN27	Scatter graph contains IV vs DV 'Measurable' axis units.	1	The scatter graph clearly shows the independent variable (Splint length) on the x-axis with units in cm, and the dependent variable (Burning Time) on the y-axis with units in seconds. Both axes are properly labeled with measurable units that accurately reflect the variables being analyzed in the experiment.
📷 AN28	Scatter graph contains IV vs DV axis Instrumental Uncertainty values.	0	The scatter graph shows uncertainty bars for the dependent variable (burning time) but lacks uncertainty values in the axis labels. The x-axis shows 'Splint length +/- 0.05 (cm)' but the y-axis only shows 'Burning Time +/- 0.01s' without the actual uncertainty values being displayed on the axis labels themselves. The criterion requires uncertainty values to accompany the axis labels and units, which is not fully present.
📷 AN29	Scatter graph contains uses crosses to plot data points.	1	The scatter graph clearly uses crosses (X marks) to plot all data points consistently. Each data point on the graph is represented by a cross symbol, with no other plotting symbols like dots or circles used. The crosses are clearly visible and properly positioned at the intersection of the corresponding x and y values for each measurement.
📷 AN30	A scatter graph trendline gradient equation shows the Final Relationship is given.	1	The scatter graph clearly shows a trendline with the gradient equation y = 6.2355x + 0.4295 displayed on the graph. This equation is in the standard Y=MX+C format where the gradient value M (6.2355) quantifies the relationship between splint length (x) and burning time (y). The equation is properly derived from the data points and represents the final relationship between the variables being investigated.
📷 AN31	Scatter graph trendline has a R2 value given.	1	The scatter graph clearly shows a trendline with an R² value of 0.9182 displayed next to the equation y = 6.2355x + 0.4295. The R² value is clearly visible and properly positioned adjacent to the trendline on the graph. This meets the criterion requirements for displaying the coefficient of determination on a scatter graph with 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	The scatter graph shows no horizontal uncertainty bars for the independent variable (IV). The IV instrumental uncertainty is stated as ±0.05 cm in the data tables, but this is not represented graphically on the x-axis of the scatter plot. Only vertical uncertainty bars for the dependent variable are visible. There is no textual explanation or justification for the absence of horizontal uncertainty bars representing the IV instrumental uncertainty.
📷 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	The scatter graph clearly shows vertical uncertainty bars on each data point representing the dependent variable (burning time). The bars accurately reflect the calculated uncertainty in repeats values from the data tables, with varying sizes corresponding to different uncertainty values (ranging from ±8 to ±90 seconds). The bars are properly positioned at each data point and visually represent the uncertainty calculations performed in the previous analysis.
📷 AN34	A Maximium gradient trendline is calculated from the lowest vertical uncertainty bar and highest horizontal uncertainty bar on the first data point, t	0	The student has not calculated a maximum gradient trendline. While the graph shows a main trendline (y = 6.2355x + 0.4295) and mentions uncertainty bars, there is no evidence of a separate maximum gradient calculation using the specified method of connecting from lowest vertical/highest horizontal uncertainty on first point to highest vertical/lowest horizontal uncertainty on last point. The data tables show uncertainty values but no maximum gradient trendline equation is provided.
📷 AN35	A Minimum gradient trendline is calculated from the highest vertical uncertainty bar and lowest horizontal uncertainty bar on the first data point, to	0	The graph shows uncertainty bars and multiple trendlines, but there is no minimum gradient trendline calculated from the highest vertical uncertainty bar on the first data point to the lowest vertical uncertainty bar on the last data point. The student has not identified or calculated this specific minimum gradient trendline with its associated equation as required by the criterion.
📷 AN36	Trendline equations for the Maximum and Minimum gradient trendlines are shown on the graph.	0	The graph shows three trendlines but only displays equations for two of them: y = 6.2355x + 0.4295 (black line) and y = -0.1079x + 26.28 (blue line). The orange/yellow line representing either the maximum or minimum gradient lacks its equation on the graph. The criterion specifically requires both Maximum and Minimum gradient trendlines to have their equations clearly displayed on the graph.
AN37	Uncertainty in Final Relationship is calculated by [(Maximum gradient value-minimum gradient value)/2 = Uncertainty in Final Relationship] formula.	1	The student correctly applies the formula [(Max-Min)/2] for uncertainty in final relationship. They show Maximum gradient = 10.99, Minimum gradient = -0.11, and calculate (10.99-(-0.11))/2 = +/-5.5 s/cm. They also demonstrate an alternative approach using actual max/min data, selecting the larger uncertainty (+/-6.09) to encompass all data. The calculation is clearly displayed with proper mathematical operations and final presentation as +6.20 +/- 6 s/cm.
AN38	State Uncertainty in Final Relationship units, using [Y axis units/X axis units] formula.	1	The student explicitly states the uncertainty of the final relationship as '+6.20 +/- 6 s/cm' in the correct [Y axis units/X axis units] format. The uncertainty is clearly calculated using maximum and minimum gradients (+/-6.09, rounded to +/-6), and the units (seconds/centimeters) correctly represent Y axis units divided by X axis units. The numerical representation and unit format meet the criterion requirements despite minor presentation variations.
AN39	State Uncertainty in Final Relationship to 1 Significant Figure	1	The student explicitly states the uncertainty of the final relationship as '+6.20 +/- 6 s/cm (1 sig fig)' in section AN26. The uncertainty value of ±6 is correctly rounded to 1 significant figure from the calculated ±6.09. The uncertainty is presented in clear numerical format and directly associated with the main result (gradient/slope of the relationship). This meets the criterion requirements.
AN40	Convert Uncertainty in Final Relationship into %Uncertainty in Final Relationship using the [Uncertainty in Final Relationship/Final Relationship grad	1	The student correctly applies the formula [Uncertainty in Final Relationship / Final Relationship x 100 = % Uncertainty in Final Relationship]. They clearly identify the values: Uncertainty = 6.09, Final Relationship = 6.20, and show the calculation step-by-step: (6.09 / 6.20) x 100 = +/- 98%. The result is properly expressed as a percentage with appropriate significant figures (+/- 100% rounded to 1 sig fig), meeting the criterion requirements.
AN41	State %Uncertainty in Final Relationship to 1 Signficant Figure	1	The student explicitly states the percentage uncertainty in the final relationship as +/-100% to 1 significant figure in section AN26. The calculation is shown: (6.09/6.20) x 100 = +/-98%, then rounded to +/-100% (1 sig fig). This meets the criterion requirements despite some formatting inconsistencies elsewhere in the report.

Conclusion (9 criteria)

Code	Criterion	AI	Justification
CO1	The research question is answered by describing the IV-DV relationship gradient trend.	1	The student clearly describes the IV-DV relationship with a positive gradient trend. In the conclusion section (CO1-CO6), they explicitly state 'as the length of the splint increases, the burning time also increases at +6.20 s/cm' and confirm 'a strong positive, linear relationship.' This description is based on their scatter graph analysis and trendline (y = 6.2355x + 0.4295). The relationship between IV (splint length) and DV (burning time) is explicitly described with the positive linear trend identified.
CO2	The IV-DV relationship gradient equation is explicitly stated.	0	The student presents two equations but neither explicitly defines the IV-DV relationship gradient. The cellulose combustion equation (C6H10O5 + 6O2 → 6CO2 + 5H2O) is a chemical reaction, not an IV-DV relationship. The final relationship 'y = 6.2355x + 0.4295' uses generic x,y variables without explicitly stating that this represents the gradient between splint length (IV) and burning time (DV). The equation lacks proper variable identification as required.
CO3	The IV-DV relationship gradient units are quoted in the conclusion.	1	The conclusion explicitly states the gradient relationship between IV (length) and DV (burning time) as '+6.20 s/cm' with appropriate units. The gradient units (seconds per centimeter) are correctly formatted and clearly represent the relationship between the two variables. While there are some additional values mentioned, the core requirement of stating the gradient with proper units is clearly met.
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 clearly states the R² value (0.91), correctly categorizes it as a strong correlation using appropriate terminology ('not perfect but still a strong correlation'), and demonstrates understanding that values >0.7 indicate strong correlation. The discussion adequately links the R² value to data reliability and correlation strength between variables studied, meeting the criterion requirements despite minor imperfections in presentation.
CO5	Accuracy of relationship is justified based on cited research of a similar area of study.	0	The student fails to justify the chemical relationship based on cited research. While two sources are cited, neither provides scientific justification for the burning time vs. length relationship. The forest fire source only mentions fuel doubling affects spread rate and intensity, not burning duration. The pyrolysis source describes wood burning process but doesn't support the linear relationship claim. No proper scientific justification connects the cited research to the experimental relationship being investigated.
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 student explicitly restates their hypothesis in section CO6 and compares it with results, confirming the positive linear relationship was supported. They reference the underlying chemistry from their background section about combustion reactions requiring more fuel taking longer to burn. While the in-text citation could be more explicitly restated in this section, the student adequately addresses the criterion by comparing hypothesis with results and explaining the chemical basis.
CO7	% Uncertainty in Final Relationship from min-max trendlines is re-stated in the Conclusion.	1	The conclusion explicitly restates the % Uncertainty in Final Relationship at 98% (rounded to 100% for 1 sig fig) that was calculated earlier in the analysis section. The student correctly calculated this from the min-max trendline variation using the formula (6.09/6.20) x 100 = 98%, then restated it in the conclusion as '+6.20 s/cm +/- 100% (1 sig fig)'. The criterion is met.
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 addresses this criterion in section CO8, explicitly stating that the 98% uncertainty in final relationship could potentially make the trendline horizontal or even negative, which would mean splint length had no relation to burning time. This directly discusses how the large uncertainty magnitude could change trend direction and invalidate the conclusion that length affects burning time. The discussion adequately links uncertainty to possible trend changes and conclusion validity.
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 demonstrates clear commentary on major experimental flaws that could invalidate results. They identify systematic errors like inconsistent burning technique, subjective ignition timing, and uncontrolled flame positioning. They discuss the impact of these issues (e.g., 'burning rate would not be controlled') and acknowledge potential invalidity concerns. The detailed error analysis table and evaluation sections show comprehensive understanding of validity threats, meeting the criterion's requirement for commentary on major concerns.

Evaluation (13 criteria)

Code	Criterion	AI	Justification
EV1	Strengths of methodology are highlighted, based on trial run modifications if possible.	1	The student adequately identifies methodological strengths including removal of invalid data from partially burned splints (RD22) and multiple repeats for data reliability. They explain how trial run modifications improved accuracy by ensuring complete burning. The evaluation section (EV1) explicitly highlights strengths and links them to reduced uncertainty. While the explanation could be more detailed, the student demonstrates understanding of how their methodological choices improved experimental effectiveness and accuracy.
EV2	Equipment choice is evaluated to reduce Instrumental Uncertainties.	0	The student fails to identify which equipment has the largest instrumental uncertainty or suggest alternative equipment with lower uncertainties. While they mention ruler (±0.05cm) and timer (±0.01s) uncertainties and conclude instrumental uncertainties are insignificant compared to repeatability errors, they don't compare these uncertainties directly to identify the largest contributor. No alternative equipment is suggested. The analysis remains superficial without the required evaluation of equipment contributions to combined instrumental uncertainty.
EV3	Comparison of a Mean Propagated % Instrumental Uncertainty vs % Uncertainty in Final Relationship from gradients is stated using [Mean Average IV % un	1	The student provides a clear comparison in section EV3: Mean Propagated % uncertainty = 0.6% vs % Gradient Uncertainty in Final Relationship = 100%. They correctly calculate the average IV and DV uncertainties (0.56% + 0.02% = 0.58%) and compare this to the final relationship uncertainty (98%). The comparison explains the two orders of magnitude difference and discusses why the final uncertainty is much larger than the instrumental uncertainties.
EV4	Major Methodological improvements suggested to improve accuracy and validity by identifying and removing specific Systematic errors that have become a	1	The student identifies major systematic errors in section EV4 and the controlled variables table, specifically: burning technique variations, inconsistent ignition methods, and lack of methodological detail causing validity issues. They provide specific, actionable improvements like specifying vertical burning position, standardizing ignition time (5 seconds), and controlling flame placement (1cm into flame). These systematic errors were previously identified as making the experiment potentially invalid, meeting the criterion requirements.
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	The student provides a comprehensive table titled 'Problems with current method' that clearly lists weaknesses in the experimental method. Each weakness includes a column for 'Impact and Relative significance' where significance is qualitatively assessed (Minor, Moderate, Major). The assessments are logical and justified - for example, burning technique is rated 'Major' due to substantial impact on burning rates, while flame extinction is rated 'Minor'. The table is well-organized with clear descriptions and appropriate significance evaluations.
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	Student provides a comprehensive table with 'Error Type' column containing both 'Systematic Error' and 'Random Error' entries. Systematic errors are correctly described as producing consistent effects (burning technique affecting rate consistently, ignition method causing consistent burning variations). Random error is properly identified as unpredictable (flame going out occasionally). Definitions align with criterion requirements that systematic errors produce same magnitude/direction effects while random errors vary.
EV7	Weaknesses in method are stated in a table with a column for ‘Problems'.	1	The student includes a clear table with the column header 'Problems with current method' which satisfies the 'Problems' column requirement. Each entry identifies specific methodological issues (burning technique, flame extinguishing, subjective ignition timing, unspecified ignition method) and explains their impact on the experiment. The problems are relevant to the experimental method and clearly articulated, meeting the criterion requirements despite minor formatting variations.
EV8	Weaknesses in method are stated in a table with a column for ‘Suggested Solutions'.	1	A clear table is present listing weaknesses in the experimental method with corresponding solutions. The table has proper structure with columns for 'Problems with current method' and 'Potential solutions'. Each weakness (burning technique, flame extinction, subjective ignition timing, non-specific ignition method) is paired with actionable solutions for future experiments. The solutions directly address the identified problems and suggest specific methodological improvements.
EV9	Improvements suggest increased Repeated data points and removal of outliers to reduce Random Errors, causing smaller Uncertainty in Repeats.	0	While the report mentions removing outliers and discusses data variation in AN11, it fails to distinguish between the two distinct processes required. It does not explain that additional data points lead to lower standard deviation, and only then can outliers outside this narrower range be identified. The report lacks specific methodology for outlier identification and doesn't demonstrate understanding that these are separate sequential processes for reducing random errors.
EV10	Improvements suggested to expand the IV data range are made.	0	The student mentions expanding the range to 20-30cm splints in EV10 but fails to provide specific actual values for the expanded IV range. The criterion requires explicit specific values (e.g., 'expand from 2-16cm to 2-30cm'). While the student discusses practicability and links expansion to trend observation, the lack of concrete numerical specifications for the new range fails to meet the criterion's explicit requirements.
EV11	Improvements suggested to narrow the IV data intervals are made.	1	The student clearly suggests reducing IV intervals from 2cm to 0.5cm increments (e.g., 2.0, 2.5, 3.0, 3.5cm) in section EV11. This specific improvement compares existing values with proposed smaller intervals and links to producing a 'more consistent trendline.' The suggestion is practically implementable as it maintains measurable precision while increasing data points for better trend analysis.
EV12	Minor Methodological improvements suggested to improve on the accuracy of the experiment.	1	The student provides multiple specific methodological improvements with clear scientific reasoning. They identify key limitations like inconsistent holding methods, subjective ignition timing, and variable flame angles. Each suggestion includes detailed explanations of how improvements would reduce errors (e.g., specifying vertical holding position, standardizing ignition time to 5 seconds, marking 1cm for flame placement). The improvements are feasible and directly target accuracy issues in their current methodology.
EV13	Suggested extension investigations, that will adapt and improve this specific investigation are proposed.	0	The student proposes only one extension: investigating thickness effects on wood combustion rate. While this builds upon the original experiment by changing a variable (thickness vs length), it lacks proper justification for how this will improve accuracy or confidence in the original findings. The brief mention of forest fire applications is insufficient rationale. The criterion requires clear explanation of why the extension will help research the original aim more accurately, which is missing.