Developing a progression model for IBDP biology

I recently completed Daisy Christodolou’s “Making good progress?”. You can see my notes here. In the final chapters, after presenting an argument building up to this, she outlines the key aspects of what she terms a “progression model”. In this post I want to line up some ideas about what this may look like in delivering the IB DP Biology course.

In her book Christodoulou suggests, and I agree, that to effectively help students make progress we have to break down the skills required to be successful in the final assessments into sub-skills and practice these. This is a bit analogous to a football team practicing dribbling, striking or defending in order to make progress in the main game.

In the book she also stresses the difference between formative and summative assessments, what they can and can’t be used for respectively and why one assessment can’t necessarily be used for both.

A progression model for biology

A progression model would clearly map out how to get from the start to the finish of any given course, and make progress in mastering the skills and concepts associated with that domain. In order to do this we need to think carefully about:

  1. What are the key skills being assessed in the final summative tasks (don’t forget that language or maths skills might be a large component of this)?
  2. What sub-components make up these skills?
  3. What tasks can be designed to appropriately formatively assess the development of these sub-skills or, in other words, What does deliberate practice look like in biology?
  4. What would be our formative item bank?
  5. What could be our standardised assessment bank?
  6. What are appropriate summative assessment tasks throughout that would allow us to measure progress throughout the course?
  7. What could be our summative item bank?
  8. How often should progress to the final summative task be measured i.e. how often should we set summative assessments in an academic year that track progress?

Key skills in biology

This is quite a tricky concept to pin down in biology specifically and in the sciences in general. What skills exactly are kids being assessed on in those final summative IGCSE or IBDP/A Level exams. I haven’t done a thorough literature review here so currently I am not sure what previous work has been in this area.

However,  I would contend that most final written summative exams are assessing students conceptual understanding of the domain. If this is the case then the skill is really, thinking and understanding about and with the material of the domain. Students who have a deeper understanding of the links between concepts are likely to do better.

In addition, those courses with a practical component, like the IBDP group 4 internal assessment are assessing a students understanding of the scientific process. While it may seem like these components are assessing practical skills per se, they only do this indirectly, as it is the actual written report that is assessed and moderated. To do well the student is actually demonstrating an understanding of the process, regardless of where their practical skills are in terms of development.

Indeed if we look at the assessment objectives of IBDP biology we see that this is very much the case. Students are assessed on their ability to: demonstrate knowledge and understanding and apply that understanding of facts, concepts and terminology; methodologies and communication in science etc.


How can we move students to a place where they can competently demonstrate knowledge and understanding, apply that understanding as well as formulate, analyse and evaluate aspects of the scientific method and communication.

The literature on the psychology of learning would suggest breaking down these skills into their subcomponents. This means we need to look at methods that develop knowledge and understanding from knowledge. Organising our units in ways that help students see the bigger concepts and connections between concepts within the domain will also help. For more on this see my previous post here. I think that understanding develops from knowledge.

I recently read that Thomas Khun claimed that expertise in science was achieved by the studying of exemplars. Scientific experts are experts because they have learned to draw the general concepts of the specific examples.

Useful sub-skills would be:

  • Fluency with the terminology of the domain
  • Ability to read graphs and data
  • Explicit knowledge of very specific examples
  • Explicit knowledge of abstract concepts illustrated by the specific examples
  • Ability to generate hypothesis and construct controlled experiments

Deliberate practice in biology

Thinking about these sub-skills, then, we can see what may constitute deliberate practice in biology and thus what would make useful formative assessments within the subject.

Fluency with the terminology can be gained through the studying of terminology decks like those available on quizlet. In addition, the work of Isabel Beck. Suggests that learning words isolated from text is not that helpful to gaining an understanding of those terms. To gain this, students need to be exposed to these words in context. Therefore there is a lot to be said for tasks and formative assessments that get students reading. Formative assessments could then consist of vocab tests and reading comprehension exercises of selected texts.

Reading and interpreting data can be improved through practice of these skills. This is an area where inquiry alone won’t help students make progress. Students need to be shown how to interpret data and read tables and graphs before making judgements. Ideally, in my opinion they should do this once they have learned the relevant factual knowledge of a related topic. Formative assessments focussing on data interpretation should therefore come a little later once students have covered a bulk of the content.

To build up conceptual understanding, students need to be exposed to specific examples related to those topics as I outlined in this post. Tests (MCQs) that assess how well students know the specific details of an example could be useful here to guide learners to which parts they know and those they don’t.

Following this we can begin to link examples together to build knowledge of a more abstract concept. Concepts can then be knitted together to develop the domain specific thinking skills: thinking like a biologist.

Formative assessments

Formative assessments could take the form of MCQs but as outlined above, vocab tests, reading comprehension activities, and other tasks may well have their place here.

Summative assessments for measuring progress

I am now thinking that to truly assess student progress against the domain, individual unit tests just won’t cut it. As Christodolou argues, summative tests exists to create shared meaning and do that need to be valid and reliable. Does scoring a 7 in a unit test on one topic of an 11 topic syllabus mean that the student is on track to score a 7? Not necessarily. Not only is the unit test not comparable to the IB 7 because it is only sampling a tiny portion of the full domain, but the construction and administration of the test may not be as rigorous as that of the actual IB papers.

Clearly it isn’t ideal to use the formative assessments described above as these are nothing like the final summative assessment of the course, plus their purpose is to guide teaching and learning, not to measure progress.

I would argue that summative assessments over the two-year course should use entire past papers. These past papers sample the entire domain of the course and performance against them is the best method of progress in the domain. A past paper could be administered right at the start of the course to establish a base line. Subsequent, infrequent, summative tests, also composed of past papers could then measure progress against this baseline.

Why should summative assessments use past papers? What not use unit tests? Unit tests, aggregated, is not the same thing as performance on a single assessment sampling the whole domain. They cannot produce the same shared meaning as an assessment that samples the entire domain. In addition the use of many single unit, high stakes tests will cause teaching to the test as well as much more student anxiety. Instead lots of formative testing and practice of recall should help to build students confidence in themselves.

Notes on making good progress?: Chapter 9

In this series of posts I record my notes from Daisy Christodolou’s book “Making good progress? The future of Assessment for Learning” It is quite excellent. You can buy a copy here.

An integrated assessment system

An accurate and useful progression model is the foundation of any assessment system because it explains how pupils make progress. SoWs and lesson plans and the curriculum can all be based on this progression model. Textbooks would be the most efficient way to bring all of these items together.

The first item in a progression model is a collection of formative questions which match up to the curriculum. The bank should be online so that pupils can access it at home or at school. Pupils should have formatives at the end of lessons or chapters and these would contain questions on new material and also on material previously taught. It could be linked up to question level analysis and if it was automated could point pupils straight back to a relevant video or worksheet on what the students had just got wrong.

Next we should have summative item banks. For difficulty model assessments this could be whole past papers or if online a computer adaptive system that makes testing shorter and more accurate. For quality based model we could use a comparative judgement system.

Finally a standardised test bank would contain be non-curriculum linked questions like the CEM tests. These are useful for setting targets.

Such a system would be beneficial because it would be coherent: a clear structure of progressing to novice to expert. It has the ability to give pupils ownership of the curriculum. It could also be self improving.

Notes on making good progress?: Chapter 8

In this series of posts I record my notes from Daisy Christodolou’s book “Making good progress? The future of Assessment for Learning” It is quite excellent. You can buy a copy here.

Improving summative assessments

The aim of summative assessments is for them to provide an accurate and shared meaning without becoming the model for every classroom activity. Rubrics of prose assessment statements are not particularly good at delivering reliability, and they can end up compromising the creative and original aspects of the task. Prose descriptors can be interpreted in many different ways. Judging in absolute terms is extremely difficult. Markers will overgrade and undergrade depending on the sample. We are much better at making comparative judgements than absolute ones.

very prescriptive rubrics end up stereotyping pupil’s responses to the task removing the justification for having them (grading creative and original work). Responses that are coached to meet the rubric pass and truly original work that doesn’t fails. Rubrics encourage coaching.

Comparative judgement offers the possibility of dropping rubrics by defining quality through exemplars not prose and by not relying on absolute judgement. It simply asks markers to make a series of paired judgements about responses. It relies on tacit knowledge of the subject expert – knowledge that is not easy to express in words.

Comparative judgement is criticised for offering little in the way of formative feedback. This is precisely the point. It decouples the grading process from the formative process. It allows classroom practice to be refocussed away from the rubric and towards helpful analyses of quality. One extremely useful resource that could be produced would be a set of annotated exemplar scripts.

Decisions about the difficulty and content of national summative exams are made by national exam boards. What if a school wants to summatively assess more frequently? To what extent can they be linked to the curriculum that the pupils are following? One solution is to outsource summative assessments, but there is still a gap between the remote standardised assessments like CEM and the formative assessments of classroom practice. It is not easy to create or interpret the results of school made curriculum-linked assessments. It can be difficult to tell if the test is difficult enough, or if it has the right spread of difficulty. Tests taken by small numbers of pupils don’t produce reliable grades. We can compare the results of teacher made tests to national assessments. The content studied over one term is simply not broad enough domain to sample from. Assessments have to sample from what pupils have learnt in that subject, not just in previous terms but in previous years.

A summative assessment can be linked to the curriculum and the most recent unit of study. However if a grade is awarded it will not be based solely on that unit and cannot be seen as reflecting performance on solely that unit. A student can make great strides with a unit but not be reflected on the summative unit as the assessment is not sensitive enough.

Summative assessments need to be far enough apart that pupils have the chance to improve on them meaningfully. However pupils will make relatively slow progress on the large domains that summative assessments are sampling. There are risks with using summative assessments too frequently.

Using scaled scores can overcome this to some extent. A scaled score converts raw marks which are not comparable (from different assessments) into ones that are. They show the continuum of achievement. Grades suggest that pupil performance falls into discrete categories when in fact it is continuous.

Notes on making good progress?: Chapter 7

In this series of posts I record my notes from Daisy Christodolou’s book “Making good progress? The future of Assessment for Learning” It is quite excellent. You can buy a copy here.

Improving formative assessments

Formative assessments should be:

  • Specific
  • Frequent
  • Repetitive
  • Recorded as raw marks

Specific questions allow teachers to diagnose exactly what a pupil’s strengths and weaknesses are, and they make it easy to work out what to do next, whereas open and complex questions like essays or real-world problems are not particularly well-suited to this. Short answer and MCQs can be very precise. MCQs, despite their reputation, are excellent for diagnosis and indicate what pupils might need to work on next. MCQs give a specific diagnosis of conceptual understanding and are labour saving.

Criticism of MCQs include that they are easy for pupils to answer, but the risk can be mitigated in several ways. You can increase the number of distractors, you can increase the number of questions, you can also include more than one right answer. Answers can be analysed at the level of the class. MCQs can target misconceptions very effectively. Misconceptions are an important part of a progression model often because they involve particularly tricky and fundamental concepts without which pupils cannot progress.

They are very easy to analyse. You can record not just whether the pupil got the question right or wrong but which distractors they chose. When the analysis is done on a topic that has been recently taught then it becomes much more helpful. We don’t necessarily need to re-teach topics but can ensure to highlight those misconceptions again if the curriculum is structured in a way to allow this. Explanatory paragraphs in the question bank for each MCQ make it very easy to give feedback. Once the feedback has been delivered the teacher can follow up with another set of similar questions to see if the pupil has understood this time around. MCQs with together with this kind of in-depth, specific and precise feedback, can form a vital part of a progression model in any subject.

Research shows that the act of recalling information from memory actually helps to strengthen the memory itself. That is, testing doesn’t just help measure understanding; it helps develop it. This is called the testing effect. This effect can certainly apply to summative tests too so long as they don’t force students away from retrieval and into problem-solving search. The power of the testing effect is that it introduces desirable diffficulties. self-testing is much more effective revision than re-reading. Re-reading makes pupils feel familiar with the content but doesn’t guarantee thought. Testing makes it clear if students have understood something.

Generally assessment should not take place too close to the period of study as we can’t make a valid inference about whether a pupil about whether students have learned the material. If a student gets the question right very soon after study we are not provided with a valid inference. Some of the questions set for recap at the start of the lesson or for homework or at the end of the lesson should cover previously learned material.

Recording grades frequently forces formative assessment into a summative model. We could simply stop recording formative assessment as this assessment aims to be responsive not reportive. If we do record marks these should not be converted to grades. When converting to grades you are asserting that the difficulty of the two assessments is the same and that you are trying to derive a shared meaning. Also, the aim of formative assessments is to set questions that are closely tied to what is being studied.

Notes on making good progress? by Daisy Christodoulou

In this series of posts I record my notes from Daisy Christodolou’s book “Making good progress? The future of Assessment for Learning” It is quite excellent. You can buy a copy here.