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New Group 4 IA scheme - Chemistry

This document explains the changes that were made in the Chemistry IA scheme, including reducing teacher and moderation workload, addressing concerns about planning emphasis, and returning summative assessment to its rightful context. It also provides guidelines for setting successful assessed design tasks in order to improve consistency.

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New Group 4 IA scheme - Chemistry

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  1. New Group 4 IA scheme- Chemistry

  2. Why the changes were made? • Response to teacher questionnaire • Reduce teacher and moderation overload to improve consistency • Addressed lightweight two aspect DC and DPP • Addressed concerns regarding planning emphasis on hypothesis • Reduced non-moderated components which were still being downgraded. • MS back to its rightful summative context appropriate for a range of skills • G4P often not suitable for assessment of written evidenced criteria

  3. IB LEARNER PROFILE IB learners strive to be: Inquirers Knowledgeable Thinkers Communicators Principled Open-minded Caring Risk-takers Balanced Reflective

  4. New mark allocation Design x 2 = 12 (25%) DCP x 2 = 12(25%) CE x 2 =12 (25%) PS x 1 = 6 (12.5%) MS x 1= 6 (12.5%) Making a total out of 48 (scaled to 24%)

  5. Design (D)

  6. Design Should the students cite materials and apparatus as a separate list? It is probably advisable but not obligatory as long as the materials and apparatus are clearly identified in procedure. Reactant concentrations, masses, volumes, etc, to be included.

  7. Design Aspect 2Control of Variables • By control of variables we mean the manipulation of the independent variable and the attempt to maintain the controlled variables at a constant value. • In a good Design task the student should have actively had to consider the control of variables. • eg, Control of temperature in rate of reaction experiments. (does a titration really give opportunity of active consideration of variables)

  8. Design Aspect 3 Sufficient data • The planned investigation should anticipate the collection of sufficient data so that the aim or research question can be suitably addressed and an evaluation of the reliability of the data can be made. • Few candidates consider the assessment of reproducibility through replication or the assessment of uncertainty through calibration of experimental set-up with a known standard. • Candidates fail to plan for a suitable number of trials in order to properly investigate, ideally through graphical means, the effect of changes in the independent variable upon the dependent variable. • Rule of thumb – 5 Data Point Rule

  9. Example considerations when assessing sufficiency of data could be: • The plan allows for the gathering of at least 5 data points to show a trend by graphical means eg. at least five values of independent variable in a rate of reaction investigation. • A plan investigating comparative properties within a homologous series, or similar, should allow for use of at least four homologues to identify a trend. It is acknowledged that any follow-up practical work may be modified if not all resources are available. • The plan allows for repeats measurements to calculate a mean eg repeat calorimetric determinations when investigation on enthalpy of reaction. • The plan shows appreciation of need for trial run and repeats until congruency in titrimetric determinations.

  10. SETTING A SUCCESSFUL ASSESSED DESIGN TASK Train them in skills either pre-Diploma program or early in Diploma course Take your time with early design activities. Better to not assess first Design activities and to really guide students as to expectations of Design

  11. SETTING A SUCCESSFUL ASSESSED DESIGN TASK 2 • Select a task in which the students already have some background knowledge and practical skills • Give them a pre-session in which to familiarise themselves with the system and the materials/equipment before they write their plan. • Students should be trained to at first select possible independent/control variables.

  12. GENERAL RULE • The more possible independent/control variables the better. Leads to • Greater variety of individualized plans. • More meaningful opportunity to design for control of variables.

  13. An Individual Research To improve the individuality of students plans and subsequent reports you could set aside time for an individual project. Offer them a list of those suggestions for which you have the materials and/or Allow students to come up with original ideas

  14. DESIGN • Do not do a practical prior to the planning task that requires an identical procedure if Design is to be assessed. • Eg. DCPIP titration for Vitamin C analysis of orange juice that is simply extended to consideration of juice samples. Not assessable for Design.

  15. SETTING A SUCCESSFUL ASSESSED DESIGN TASK 3 EXAMPLE FACTORS EFFECTING SUPERCOOLING IN SALOL

  16. SETTING A SUCCESSFUL ASSESSED DESIGN TASK 4 SALOL Timeline • Session 1 (80-90 mins): Task is set to the students. Students will draft initial ideas re. independent variables and experimental procedure. They may use rest of double period for preliminary trials. • The plans will be written as homework and submitted prior to Session 2 for assessment. • The plans are marked and returned to students. These are the final Design marks entered on 4PSOW. • Session 2 (160 mins!): Students carry out action phase following their plans. Since the plans have now been assessed for Design the teacher is free to suggest modifications to any student whose plan was unworkable (possibly owing to unavailable materials) or overly simplistic in order to help them generate data to satisfy other criteria.

  17. Possible Variables Cooling Rate Degree of stirring/agitation Initial Temperature Mass of compound Surface area of sample compound Identity of vessel Chemical Structure of Compound Composition of binary mixture (possible independent) Example selection Control (measure/active) Independent Control (active) Control (active) Control (passive) Control (passive) Control (passive) Control (active) SETTING A SUCCESSFUL ASSESSED PLANNING TASK 5 SELECTING THE VARIABLES

  18. Data collection and processing (DCP)

  19. Data Collection Processing DCP NOW APPLIES TO QUANTITIVE DATA COLLECTION EXERCISES. No purely qualitative data collection exercises for assessment of DCP Associated relevant qualitative data needed (annotate for moderator if you felt there was nothing relevant to record). Uncertainties to be included.

  20. DCP • Processing of raw data may include: • subjecting raw data to numerical calculations • using graphical means to derive a quantity or relationship. • The simple transformation of raw data into graphical form is not sufficient to fulfill completely the criterion unless there is some expectation that further quantitative or qualitative information will be extracted from the graph.

  21. DCP • For example the plotting of volume of gas produced against time in a rate of reaction experiment would not completely fulfill this aspect but if the student has compared quantitatively gradients for rate curves obtained under different conditions then the aspect can be assessed fully. • Similarly a titration curve where raw pH and volume of acid/base measurements are plotted is sufficient only so long as the graph is used to obtain further data, such as a pKa value of a weak acid or the titre.

  22. Data Collection and Processing • Increasing minority of schools encouraging meaningful treatment of errors or uncertainties in DCP (DPP). • HL and SL same expectation based on Topic 11 • The TSM 1 should be referred to for guidance in this area. (see workbook)

  23. DCP • Relatively small number of graphs presented for moderation and their poor quality overall. • Poor use of Excel. Contemporary versions of Excel can be used to great effect in DPP but the normal expectations of graphing , i.e. labeled axes with units, best-fit lines and curves, etc, must still be observed, as well as the candidate’s individual contribution being evident. • A graphing program that does not permit user control over the processing or output is not suitable for assessment of this criterion.

  24. DCP • Although the data collection phase may be carried out in groups the actual recording and treatment of data should be independently undertaken if DCP is to be assessed. • Online data collection exercises are suitable for assessing DCP aspects 2 & 3.

  25. Conclusion and evaluation (CE)

  26. Conclusion and Evaluation • Currently low scoring • Many candidates fail to compare their results to literature values where appropriate. • Often no valid conclusion with an explanation that is based on the correct interpretation of the results. • Little evidence that candidates make any attempt at background reading or research in order to interpret their findings.

  27. CE (con’t) • Most candidates attempt to evaluate the procedure and list possible sources of error. • Often this evaluation is superficial • Candidates should attempt to identify reasonable systematic errors. • If a total % uncertainty for DCP is determined then use to assess if the final result was explainable by random error or required the consideration of systematic errors. • Many candidates are able to make appropriate suggestions to improve the investigation following the identification of weaknesses.

  28. Manipulative skills (MS) (assessed summatively) This criterion addresses objective 5. *Instructions may be in a variety of forms: oral, written worksheets, diagrams, photographs, videos, flow charts, audio tapes, models, computer programs, and so on, and need not originate from the teacher.

  29. Personal skills (PS) (for group 4 project assessment only) This criterion addresses objective 4. The assessment can be assisted by the use of a student self-evaluation form, but the use of such a form is not a requirement.

  30. GENERAL PROBLEMS & CONCERNS Simplicity of task • Some tasks are being set that are too simple for IB diploma level. Affects all criteria and severely distorts the moderation process. • One type of simplicity is when the investigation is not pitched at a level that is appropriate for the application of IB Diploma level concepts and techniques. Eg. separating a mixture of sand and salt or calculating the density of a penny. • If students are coming in the Diploma with no prior practical skills then maybe such activities have a role to play early in the course but should not be used for formal assessment purposes and should not take up a significant proportion of the total practical scheme of work.

  31. Simplicity 2 Minimum of data Well constructed data tables with uncertainties that contain only two or three pieces of data. Is this enough to merit the full marks awarded by the teacher?! Wouldn’t that be unfair on students set much more demanding tasks that they have only been able to partially fulfill.

  32. SIMPLICITY 3 If you set simple tasks as training exercises or as an introduction to addressing the criteria then there is no problem as long as you do not enter resultant marks on the final 4PSOW forms.

  33. PRESCRIPTIVE INVESTIGATIONS • Do not give focused aims or procedures if Design is to be assessed • Do not provide ready formatted data tables/column headings (DCP Aspect 1). • Do not provide stepwise guide to calculations or specify which quantities to plot graphically (DCP Aspect 2) • Do not give leading questions to guide CE

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