In our second blog post from Brenda Walpole, she explains how to prepare Biology for the IB Diploma students for assessment. Brenda is an author from our Biology for the IB Diploma series. She has taught IB for around 25 years at a top IB school in England and is also a teacher trainer.
You can listen to Brenda discussing teaching ideas with fellow author and teacher Andreas Tsokos in our Brighter Thinking Podcast episode ‘Developing essential skills for IB Sciences’. You can read Andreas’s latest post here.
You can also watch a webinar with Brenda’s top teaching tips and download her webinar presentation.
Preparing students for IB exams
Our students are a mixed and varied group with many aims and aspirations. Some will be heading to university to become scientists while others will never look at a test tube again. Students’ objectives are likely to influence the amount of time and effort they put into exam preparation. But whatever they plan to do, all of them must pass their IB exams if they are to obtain their diplomas, and as educators, we must help them achieve their full potential.
Some aspects of exam preparation apply to all subjects and all exams; it is essential to make sure that the whole syllabus has been covered as the IBO will set questions right across the course. Checking notes against the syllabus and addressing any gaps in revision sessions can help. For students who are not working in their first language it is important that they are confident with technical vocabulary. Other aspects of preparation must be tailored to the ability and requirements of the student.
The end-of-course exams for the External Assessments in science are worth 80% of the final grade, with the remaining 20% being made up by the Internal Assessment of a scientific investigation, which is moderated by the IBO at the end of the course. At both Higher Level (HL) and Standard Level (SL) there are just two exam sessions. The allocation of marks and type of questions used are shown in Appendix 1.
Multiple choice
It is a common misconception that multiple-choice questions are easy and quick, but this is not the case for IB exams. Several types of question are used – some are a simple choice, such as identifying a molecule from a diagram or calculating an answer. There are also many potential pitfalls, such as the use of negative questions, for example “Which of these molecules is not a carbohydrate?”, and the use of tables of four potential answers where only one is correct, for example:
| I | II | III | |
| A | Oesophagus | Bronchiole | Rib |
| B | Trachea | Oesophagus | Bronchus |
| C | Oesophagus | Trachea | Lung |
| D | Trachea | Bronchus | Lung |
It is important that students have plenty of opportunities to practise the different styles of multiple-choice questions so that they become expert at spotting the patterns in them.
In the example above, it may be that a student does not recognise all the structures that are labelled in the given diagram. However, if they can identify one it will reduce the number of options for a correct answer. If they know that structure I is the trachea they can eliminate two answer options and have already reduced the chance of making an error by 50%. If they have no idea of the answer, emphasise that it is always worth taking a calculated guess, as there is a one in four chance of being correct every time. Last but not least, do make sure that students are adept at answering on the grid that is provided, and if answers are being written, that students use pencil so they can make corrections.
Data-based and short-answer questions
Data-based questions provide information for analysis, which may be in the form of graphs, tables or diagrams. Short-answer questions are usually fact based and may require explanations or calculations.
In both cases students should be encouraged to look for two crucial components. Firstly the command terms and secondly the number of marks awarded. These will give an indication of the depth of response required and the amount that they should aim to write.
Command words include:
State – just a simple statement is needed, usually for 1 mark.
Compare – in this case there must be a comparison, with two phrases linked by conjunctions such as ‘whereas’, ‘but’ or ‘on the other hand’. No marks will be awarded unless a comparison is made.
Deduce, calculate, analyse, identify – work out from the data given.
Discuss – here a point of view should be presented in a slightly longer answer.
Explain – a longer answer is needed with details of the process being addressed.
The allocation of marks gives further hints about how to address a question. Examiners will have a mark scheme which lists the acceptable answers. If 3 marks are to be awarded the student must include three separate points to achieve all three.
Where mathematical data is used, ensure your students know to use the correct units in their answers. If there is a specified notation in the syllabus, for example in genetics problems, they must use this to avoid losing marks, e.g. for blood groups, IAIB – not AB.
Extended-response questions – essays
Included on Paper 2, there will be a choice of one of two questions at SL and two of three at HL. These questions are usually divided into three sections each with their own allocation of marks. Even a weaker student should be able to answer one or two of the sections, for example:
- Outline the phases of mitosis. (4)
- Discuss the advantages and disadvantage of genetic screening. (7)
- Draw a labelled diagram of the human kidney. (4)
Encourage students to read the exam paper carefully. If genetic screening in the above example is a blank for them, they must choose another question, even if they know all about mitosis and the kidney, as the number of marks to be awarded for part (b) is so high. Students who are not confident about writing at length should look out for questions involving the command word ‘draw’ to pick up useful marks.
Finally, suggest that students revise appropriately. The brightest and best will be able to tackle harder topics such as advanced photosynthesis and respiration. However, those who struggle with biochemistry would do better to spend their time ensuring they can tackle all the other topics well rather than spending hours on chemiosmosis. Familiarisation with the exam style and content builds confidence and aids revision, so use all the questions that are available to help.
Appendix 1: Details of External Assessment
Standard Level
Paper 1 – 1 hour 30 mins – 36% of final grade – 55 marks available
Paper 2 – 1 hour 30 mins – 44% of final grade – 50 marks available
Paper 1A – 30 marks
30 multiple-choice questions
Paper 1B – 25 marks
Four data-based questions related to the syllabus and experimental work
Paper 2A – 34 marks
Data-based question
Short-answer questions on SL material
Paper 2B – 16 marks
One of two extended-response questions
Higher Level
Paper 1 – 2 hours – 36% of final grade – 75 marks available
Paper 2 – 2 hours 30 mins – 44% of final grade – 80 marks available
Paper 1A
40 multiple-choice questions on SL and HL material
Paper 1B
Four data-based questions related to the syllabus and experimental work
Paper 2A – 48 marks
Data-based question
Short-answer questions on HL and SL material
Paper 2B – 32 marks
Two of three extended-response questions
