Internal assessment

The individual investigation is a 10 hour piece of work that accounts for 20% of the final IB Chemistry grade. It allows students to demonstrate and apply their skills and knowledge whilst at the same time pursuing an area of interest. The internal assessment task consists of just one scientific investigation which should take about ten hours and be presented in a 6-12 page write up (including references and appendices). The investigation should be complex and commensurate with the level of the course though SL students will be marked against the same criteria as HL.

The investigation should have a purposeful research question together with the underlying scientific rationale for it. This can be through the collection of primary information or through data-based analysis. Some of the possible tasks include:

• a laboratory investigation using a hands-on approach
• analysis/and or modelling using spreadsheets
• using a database to extract information leading to graphical analysis
• A hybrid of the above three
• The use of an interactive and open-ended simulation

The individual investigation is marked against 5 criteria with a total mark allocation of 24:

• Personal Engagement (2)
• Exploration (6)
• Analysis (6)
• Evaluation (6)
• Communication (4)

Exemplar work

The piece of work below was graded and moderated at 22/24 and achieved a grade of a 7. Use it as a basis to frame your lab but remember, it is not a perfect piece of work and has room for improvement.

The lab below is an IB sample that was graded 23/24

Moderator comments

Personal engagement: 2/2

Moderator’s comment: This is a nicely original investigation where the student has shown plenty of interest, curiosity and personal initiative.

Exploration: 6/6

Moderator’s comment: The topic is identified and a clear and relevant research question stated. The background information is detailed, relevant and helps provide understanding of context. The methodology is suitable, although the stoichiometric balance of reactants is not fully established, so it is not clear that the hypochlorite ions are in excess as stated and required but otherwise looks like data will be relevant, reliable and sufficient. There is sufficient attention to safety.

* This indicator should only be applied when appropriate to the investigation.

Analysis: 6/6

Moderator’s comment: The report includes sufficient relevant quantitative and qualitative data to support a detailed conclusion. The data processing is sufficient, and the extrapolation of the light intensity graph is accurate. There is consideration of impact of measurement uncertainties, and the processed data is interpreted so that a valid conclusion could be deduced.

Evaluation: 5/6

Moderator’s comment: The conclusion falls short of being completely detailed, since the student could have concluded as to the linearity of the proportionality between concentration and initial light intensity rather than just saying a positive correlation. The conclusion given is justified in terms of context, and the student then discusses strengths and weaknesses, although he or she could have possibly discussed why the graph line doesn't pass through the origin. This possibly implies systematic error. There were appropriate improvements and extensions. 5/6 boundary. The lack of precision (linearity) in the concluding statement is a significant weakness, and we settled on 5.

Communication: 4/4

Moderator’s comment: The report is structured reasonably well, although the procedural section is written in continuous prose form that wasn’t as clear as it should have been and it drifted into the quantitative analysis. However, there is enough detail overall, and the use of terminology and conventions is appropriate. The data needn’t have been given as an appendix, but it did still remain within the page limit. This is borderline 3 or 4. Went on the lower side of a judgment call in Evaluation, so settle on the upper side here.

The lab below is an Ib sample, graded at 23/24

Personal engagement: 2/2

Moderator’s comment: Plenty of evidence present of personal input, interest and curiosity. Student has really tried to go the extra mile to make this a meaningful scientific study.

Exploration: 6/6

Moderator’s comment: The topic is clearly identified with a focused research question stated (6). The background information given is relevant, quite detailed and enhances understanding (5).

The method for determining tannin concentration by titration has come from reference 7, which is a Royal Society of Chemistry publication, which indicates a sound method. However, is the change in period of the blue bottle experiment really a rigorous measure of antioxidant properties? Possibly not, but the student is really trying to be creative. It is a demanding procedure where the independent variable (concentration of tannin) has actually been determined experimentally as well as the dependent variable (time for oxidation to occur). This is so creditable, since many students would just make an assumed relationship between aging time and tannin concentration. There is full awareness of safety (6). There is so much to positively credit, so it is worthy of 6.

Analysis: 6/6

Moderator’s comment: There is plenty of data and two sets of processing relating to the titration and the rate of oxidation. The processing is accurate and enables a conclusion to be drawn. Uncertainties are considered through the calculations and in the graph. The student correctly interprets the processed data.

Evaluation: 5/6

Moderator’s comment: A conclusion is drawn, in that the time of oxidation is directly proportional to tannin concentration, that is relevant to the research question and is consistent with the data. The justification in terms of scientific context is not strong, although in reality this is a complex phenomenon beyond easy explanation. The evaluation of weaknesses is valid but hasn’t really identified strengths. There are suggestions for modification.

Communication: 4/4

Moderator’s comment: The source of the tannin titration data-processing method could have been more explicitly acknowledged. However, overall the report is structured and clear with nearly all necessary information on focus, process and outcomes present and presented in a coherent way. There is a lot of information packed into this report without it becoming hard to follow. Plenty of referencing, although in some places it is not clear what has been sourced. Overall, though, excellent.