Exam Advice – the Devil is in the Details

By Thursday, October 31, 2013 , , , , 0

I know it may well seem that the exams are a long way off, but actually, they could be ‘just around the corner!

The November exam session is about to start and already, some of my colleagues have got extended essays to mark.  Coupled to this, the subject reports have recently been released on the Online Curriculum Centre (OCC).

A quick word about the OCC before we drop into the advice we can glean from the reports.  The IB’s OCC has had a chequered history.  It was set up to provide a mechanism for mutual support for teachers.  Initially it was really awful, but a large injection of cash made it the thing it is today, which is pretty good.  The reason I am commenting on it now is because the OCC is, and will be, as good as we make it.  We should all look at it and contribute where we can – because it is better that way.  Get on the OCC, and make it one of your ‘favourites’, so you have a quick link.

If you do not have access to the OCC, ask your Director of IB – they can get you a username and password.  These two pieces of info plus your school’s IB number are all you need.

The Physics exams are time-zoned – there is one for the US (time zone 1) and one for the rest of the world (time zone 2).  In both cases, the exam reports show evidence that the number of blank responses increases towards the end of P2 and P3.  This suggests quite strongly that the students are having problems with ‘timing’.  Teachers need to respond to this.

It is absolutely vital that students practice exam questions and the marking schemes.  When working through the material, they should focus on topic areas – looking at questions that link to particular areas.  The questions need to be tried and only then, should the marking schemes be considered.  However, full papers are also needed – under timed conditions.  And I think it is important to push the students on where they spend their time in the exam.  A reminder is often necessary, that the aim is NOT to do any questions 100% perfectly – the aim is to get as many marks as possible, in the time available.

The multiple choice papers are considered by the IB as an excellent way of testing exam timing – so use they – there are plenty out there.  If you struggle to find enough, then remember there are papers that easily go back to 2000 – just be careful about checking all the questions individually, because the syllabus changed in 2003 and 2009.

The focus of the questions has been analysed by the IB examiners and the main problem areas are probably worth noting here, although to be honest, there are really few surprises.  In each case, I will state the area and add my own thoughts:

  1. Silly lost marks.  This is where the students are simply not being careful enough – they are throwing away marks that they should all get.  For example, drawing lines and smooth curves through non-linear data.  The IB (like most boards) will use the term ‘draw a line’ to mean ‘draw a straight line or curve’.  It is amazing how many students draw a straight line through clearly curved data point.  Also, when a curve is drawn, it is not a single smooth curve but rather, an jazzed or shaded curve – which again, will often not gain the mark.
  2. Free body diagrams are poorly drawn.  The students are way too relaxed about them.  They will often draw the diagram but not ensure that the lines representing the forces are the correct length.
  3. SHM – always a tough one.  This topic is hard because conceptually, students find it difficult to grasp the fact that such motion is shown by an object which is NOT in equilibrium.  Students mix up ideas on the issue of ‘equilibrium’ and often think that this means that the object is in some ‘constant’ state of motion!  SHM is also very demanding mathematically – which catches a lot of students out.  Although differentiation is not actually needed, it really makes your life easy if you can do it.
  4. Faraday’s and Lenz’s laws – all teachers know this area is a nightmare for students – conceptually tough and mathematically tough.  In truth, it is likely that electromagnetism if the hardest part of almost any course on physics.
  5. GPE when not close to the Earth.  Students forget that the value of g is not a constant and they must use a formula for it.

In all the above cases, the best way forward is to focus questions in the class on these areas – keep going through them until the students ‘get it’.

I am now going to finish this with a moment of controversy.  For those that have seen the reports, you will be aware that there are a number of areas that students do poorly on and they simply shouldn’t.  For example, the above case of the line drawn through curved data points.  I would argue that this is in part, the IB’s fault!  If the question were phrased along the lines of “Draw the best straight line or curve through the data points”, then almost all students would get it right.  Students get caught out by the phrasing.  There is another aspect of the IB questions that catches students (and teachers) out and it is a major frustration for teachers because there is almost nothing we can do about it – the question where the words in the question are not clear enough to allow the students to know what they should do.  As an example, if anyone reads the reports they will see that students did very poorly in answering the question (TZ1) on effectively two-slit diffraction.  There was a question requiring them to explain why there was a zero of intensity at a particular point.  Most students either did not answer because they did not know what to write, or they started talking about destructive phase differences (which should be a good answer!).  However, the marking scheme required ‘calculations’.  The students were required to calculate the distances from the two different sources to the point on the screen.  Then to show that this was half a wavelength.  This kind of thing is actually fine, however, the mistake here was not due to the students, it was the IB’s fault – the question had nothing in the key which actually led the students to know that they should do the calculations – hence most didn’t.  The question should have started along the lines “By considering the distances of the sources to the point on the screen, show that …”.  In this way, there would have been a clue.

We will talk later in the academic year, about the importance of the G2 form, but it would have been useless in these cases, because you only know about the flaw in this question once you are able to see the marking scheme – months after the exam.

So where are we – we drive them forward, focusing on papers, focusing on the detail of the tough areas and focusing on exam timing.

There is no doubt that the IB exams are very tough, and at times may seem a little unfair.  However, knowing this, and knowing how to limit the negative aspects, will allow us all to give our students the best possible chance to show how good they are.

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