IB Biology HL Internal Assessment Example

Research question clearly articulated within a specific, discipline-appropriate context linking psychrotrophic bacteria, pH change, and milk spoilage.

Focused background discussion connecting consumer behavior and financial implications to the detection of milk spoilage.

Step-by-step procedure, variable table, and photographs provide most details necessary for reproducibility.

Explanation of key methodological choices (sample replicates, volume, duration, instrument use) demonstrates understanding of data sufficiency.

Sampling schedule lacks precise times and rationale (e.g., exact days), reducing reproducibility clarity.

Light exposure condition is not quantified (no irradiance or lux specified).

Minor conceptual confusion in describing lactic acid as “natural bacteria.”

Null and alternate hypotheses are mislabeled, indicating a misunderstanding of hypothesis conventions.

Raw data are comprehensively tabulated, with means, standard deviations, and graphs provided.

Processed table of mean pH changes and percentage changes is accurate and well organized.

Qualitative observations table complements quantitative results and supports data communication.

Units are missing on some axes and in the variables table, undermining clarity.

Uncertainty propagation in calculated means and percentage changes is absent; discussion focuses only on instrument resolution.

ANOVA analysis contains incorrect degrees-of-freedom and misidentified critical value, indicating significant inaccuracies.

Large variability in some trials is presented but not critically interpreted within the discussion.