Setting the grade boundaries

Paper 2

The meeting usually starts with trying to set the grade boundaries for Paper 2. In the room will be actual student scripts with marks around the suggested ranges for the boundaries. The first thing that is looked at is the completed teacher feedback forms from all the teachers. The results from the ticked boxes are given in the form of statistics e.g. 89% of those who responded thought the exam was of a similar standard to the previous year. Then each written comment on all the forms is looked at individually. The team take each point seriously and discuss whether they think the teacher has a valid point or whether they disagree with the point that the teacher is making. Later, when it comes to writing the Chief Examiner’s Report the team’s response to these points will often be included. The Principal Examiner for Paper 2 then sums up the strengths and weaknesses of the paper in terms of the marking and the actual process of deciding the boundaries begins. The boundaries have to be set so that they agree with the grade descriptors and each member of the team has the descriptors prominently in front of them. The first boundary to be set is the 3 / 4 boundary. In the light of the suggestions for the boundary from the individual team members and the comments that have gone before the Chief Examiner suggests a mark, say 41 out of 95 (for the HL paper). Several scripts that achieved that mark are selected and each member of the team separately looks at each script and decides independently whether they think it is a clear Grade 3, just on the 3 / 4  boundary or a clear Grade 4. The ASAM then asks each in turn what their verdict is. If the consensus is that the mark of 41 is a clear Grade 4 then scripts of 40 or even lower will be looked at and the process repeated. On the other hand if 41 looks to be a clear Grade 3 then scripts of 42 or even higher will be looked at etc. The process is repeated until the consensus is that the mark is a very weak Grade 4 and that mark is taken as the lowest mark that must be achieved to gain a Grade 4 on that component on the exam.  It always does seem quite amazing that a difference of just one mark in 95 can make a difference as to the grade but the process, which relies on the experience of the Grade Award team, very rarely results in any strong disagreement. If there is some disagreement then grade boundary scripts from the previous examination session can be looked at to ensure that the standard is not changing from year to year. The process is then repeated for the 2 / 3 boundary, the 1 / 2 boundary and then the 6 / 7 boundary. The 5 / 6 and 4 / 5 boundaries are achieved by extrapolation. 

Paper 1

Paper 1 is a problem to grade as there are no actual scripts to look at since the marks have been achieved by optical reading and the candidates are unable to explain how they arrived at the particular answers they gave. A list is prepared so that the questions can be put in order of how many of the students gave the correct answer and the common distracters can be identified. As with Paper 2, the teacher feedback comments are closely scrutinised. If the comments are valid and the team feels that some students will have been disadvantaged then the question can be omitted and the paper marked out of a total of 39 instead of 40. Similarly if the question is slightly ambiguous or two answers could indeed be correct then the team can authorise two correct answers for a particular question. Occasionally a perfectly good question has to be deleted to be fair to all candidates.  This is when there has been a problem in the translation to either Spanish or French.

  
Since both Papers 1 and 2 are testing the same core material (and AHL at Higher Level), albeit in a completely different way, the IB has decided that the same percentage of candidates should get the same grades as on Paper 2. So if, for example 14% of the candidates gained a Grade 7 on Paper 2 then the computer calculates the mark out of 30 (SL) or 40(HL) needed on Paper 1 for 14% of the candidates to achieve a Grade 7 and that sets the 6 / 7 boundary and so on for the other boundaries. This is a crude method but it is probably the fairest as there is no other hard evidence upon which to make the decision.

Paper 3

Paper 3 follows a similar process to Paper 2 as the actual scripts are available for the team to grade. The comments on the feedback forms often suggest that the questions on one of the options appear to be easier than the others (or one of them appears much harder than the other options). The marks at IBCA are the total number of marks that students scored on the total paper and are not broken down by Section A or Section B (options) so the paper cannot be graded by the options answered but only on the overall score. In fact when marking Paper 3 it is reassuring to see that when the marks achieved per option have been analysed afterwards they have been found to show very little difference. So the statements about the disparity among the options are usually due to perception rather than reality in terms of how the students perform.

The final Grade

Once the boundaries for all four components have been set they are fed into the computer and then compared with teacher predictions and previous year’s results. Histograms can be looked at too to see if there are any obvious differences to former years. Teachers’ predictions tend to be good with teachers slightly over predicting rather than under predicting. Usually about 80 % of the grades are exactly in line with teacher predictions and if +1 or -1 grade is then included it is usually more than 90% in agreement. To further emphasise this, the predictions for individual students from a few schools where there is a long history of accurate predictions are checked to confirm that there are no serious anomalies. Once the team and the IB are satisfied with where the boundaries have been set the grade boundaries are signed off by the Chief Examiner (or one of the Deputy Chief Examiners) and the computer then prints out the overall results for each school and the individual result for each student by school.

‘At risk’ candidates

The computer identifies all the students who are ‘at risk’. That is the grade they have achieved is two grades different to the grade the school predicted and their marks are close to a boundary. The Paper 2 and Paper 3 scripts of these students are obtained and much of the remainder of the Grade Award Meeting is spend remarking these ‘at risk’ scripts to ensure that no student has been disadvantaged through error or through the poor marking of a rogue examiner. These scripts which are remarked by a senior examiner are remarked and labelled ‘AR’. The ‘at risk’ mark is then the mark used to recalculate the student’s overall grade.

Teacher observer

Any practising IB Diploma Chemistry teacher can apply to become a teacher observer at Grade Awarding. It is a good experience to see how the process works and of course it also ensures that the process is transparent. The teacher observer is often encouraged to give their own view of the examination papers and the teachers' comments but they are not allowed to take part in the actual decisions made to set the boundaries or to do any ‘at risk’ marking. If you would like to apply to become a teacher observer then you should approach your school’s IB coordinator. If you are required to go to Cardiff then all your travel and accommodation expenses will be met but there is no actual payment for attending the Grade Award Meeting.

Actual component and overall grade boundaries

The actual raw mark grade boundaries for each component paper and the IA and the overall percentage mark required for each grade  can be found in the Chief Examiner's report which is published on My IB after each session has formally ended. As an example, the breakdown for all the components on the May 2019 examinations at both SL and HL is given on the page on Grade boundaries.