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.

Sub-skills

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.

Reflections from examining 2018

This season I marked 140 IB DP Biology HL Paper 2 Timezone 1 papers. It was unusual for a couple of reasons: 1) I managed to pass the qualification marking on the first attempt for the first time in six years! 2) I managed to complete my marking target within seven working days and nine days before the deadline – the first time I have managed to complete the work so quickly.

I felt that this years timezone 1 exam was very straightforward to mark. This was particularly evident in the data analysis responses where the mark scheme was much easier to interpret than I recall previous years being.

Qualification

To qualify for marking, normally there are practice scripts and qualifying scripts to mark. The practice scripts are a chance for you to view comments from the senior examining team, so when undertaking these it pays to go very slowly, really thinking about how the mark scheme applies in each question and when you have marked each question, checking your own marking against the comments by toggling on the annotations. Using this method you may become quickly aware of any small details in the comments that you have missed.

In the past when I have undertaken the qualifying scripts I have opted to mark them in bulk and then submit them in bulk, so I would only submit the scripts once I had marked all of the papers. This year, instead, I submitted each script after I had marked it. This gave me the advantage of being able to read the annotations on each of the qualifying scripts, check my tolerance and adjust my marking of each of the subsequent qualifying scripts. I think this may have been a primary reason why I qualified first time.

Student misconceptions on the paper

I marked 140 scripts and when you mark that many certain themes begin to emerge. This year worryingly a large proportion of candidates were conflating the mechanisms of global warming with holes in the ozone layer. This is not a new thing and it is a problem that I have noticed in previous years but this year the sheer number of candidates writing a confused response to the question on the mechanisms of global warming was staggeringly impressive.

In 2018, 18-year-old students are still writing that carbon dioxide creates holes in the ozone layer and this is what heats up the planet – or something similar. This needs to be addressed. A teacher or teachers somewhere must be teaching kids about the ozone layer.

Now I struggle to believe that this is the result of their biology teachers (who most likely will have studied this subject to sime depth and understand the science) and I am wondering if this is the result of colleagues in other subjects unrelated to science. We know that there is a lot of confusion about climate change in the media and that the scienitific debate is often misconstrued in the popular press. We also know that this is an issue of global importance and for that reason, other subject teachers may well address it. IB student could meet it in TOK, studies in language as well as geography and other teachers. I am wondering if there are some miseducated teachers out there who are confused on the issues of climate science and are confusing their kids. This would be a great area for practitioner research and opens up the question about the professional responsibilities of teachers who have a particular subject specialism: should teachers who are well educated on a particular topic be responsible for sharing that knowledge with colleagues who may also approach this topic in the own teaching?

(on a side note a colleague previously told me that XX and XY chromosomes were “a lie” in a discussion on LGBTQ+ issues in school).

Other misconceptions that became apparent were:

  • Candidates thought that water was an organic molecule
  • Candidates didn’t understand that DNA transcription/translation = protein synthesis = gene expression = expression in the phenotype.
  • Not understanding that linked loci are genes on the same chromosome not in the same place.

Common factual errors were:

  • Few candidates knew that glutamic acid is replaced by valine.

What I learned about teaching biology this year 17-18

In 2016 I wrote this blog post. My answer to that question is now decidedly, yes. Content is King.

In this post, I want to explore why this is the case and outline what my ideas are now in relation to teaching biology.

The importance of content?

First, I should point out that a re-reading of my 2016 article makes me realise that I never concluded by suggesting content wasn’t king. Like all good questions, the article title helps to stimulate thought and a discussion about where we are at in our beliefs and in defending those beliefs. Really, the argument I was making was that teaching is not all about teaching content, but about teaching content AND encouraging critical thought with that content matter.

Content underpins everything. It underpins thinking. You can’t think without something to think about. It underpins understanding. You can’t understand something that is not represented as a propositional claim at a basic level. You can’t develop “skills” that aren’t grounded in some form of understanding.

When I am talking about content, I am referring to facts or propositional knowledge, statements that are thought to be true and are about the way the biological world is.

Propositional knowledge then must have primacy in teaching biology. To my mind, currently, propositional knowledge can be broken up into facts and concepts. Facts cannot be understood, they can only be known. Whereas concepts can be known and understood.

I think that to achieve deep, flexible, biological knowledge (flexible in the sense that it can be thought about in the abstract and applied in new situations) students need to achieve a conceptual understanding of the major themes in biology.

To do this they must first meet domain-specific examples. From those examples, they can then begin to pull out the commonalities to allow the mind to achieve an understanding of an abstract concept. My post here outlines how I went about this when teaching natural selection this year.

Learning domain-specific facts cumulatively builds to domain-specific conceptual understanding which accumulates in the learner being able to think in terms of these concepts and apply them elsewhere.

The importance of presenting content in the “right” sequence

Related to the idea of sequencing teaching so that we build up to conceptual understanding from specific examples, is the idea that we need to sequence teaching to avoid cognitive overload. To do this we need to think about which areas of the curriculum provide just enough challenge to engage students but not so much so they are overwhelmed.

In teaching biology, I think this is best achieved by teaching those areas with the least new propositional knowledge for the learner. Once the learner achieves mastery of this new knowledge then we can begin to add more.

In this sense, when trying to teach the understanding of the relationship of structure and function we may wish to look at studying the function first of any new example, before looking at the structures that support that function. Developing knowledge of the function of something might contain less instances of “facts” than the discrete structures that build up that function.

Once we have looked at lots of examples of, say, the relationship between surface area and diffusion, students will build up to the understanding of the relationship generally, and hopefully be able to apply this in new and novel ways.

Retrieval practice embedding content for the long-term

Drill and kill, right? Apparently not. My reading this year has convinced me that giving students the chance to practice retrieving information, not only builds their confidence that they can perform, and therefore reduces stress but also improves their ability to retrieve that information and therefore improves its storage in long term memory.

The same goes for learning the language of the subject and so now I try to begin my lessons with a fun low stakes retrieval practice activity. Low stakes in the sense that I do not record results and store them; students are not graded. For this I have prepared a deck of quizlet terms for the DP biology course and I alternate between using these or simply giving students a series of MCQ’s from last lesson, last week, last month and last term.

Interleaving & spaced practice – what might this look like in biology?

A year ago, on the Facebook AP/IB Biology teachers group, I first asked the question of what interleaving might look like in a biology course. I had been hearing a lot about interleaving during meetings and inset training from our DP Coordinator who is a Maths teacher. It seems that interleaving has been studied quite a bit in mathematics education.

When I asked the question, hardly anyone was aware of this concept amongst the biology teachers and I was stumped. I now have some ideas.

Interleaving or spaced practice is the idea that instead of learning all the content for a particular topic at once or in a set of continuous lessons, you space out the learning over time, revisiting topics over time.

In my experience, I have always taught a topic like cell structure and then moved onto the next topic, maybe membrane structure followed by membrane function – and I think that this is true of most biology courses.

In an interleaved curriculum these topics would be spaced out in time. Let’s imagine you have a 60min lesson every day with the same class, so five lessons a week. In an interleaved curriculum you may devote Mondays to cell structure, Tuesday to metabolism, Wednesday to plant physiology, Thursday to animal physiology and Friday to retrieval practice.

You would then teach the content of these units side by side over a number of weeks. It sounds a bit crazy but it has been demonstrated to improve long-term retention of learning and I am also excited by the possibility for the conceptual links you can make by teaching in this way.

 

Sequencing facts before concepts: natural selection

I have spent a fair amount of time this year reflecting on the application of cognitive science principles in my own biology teaching. There has been plenty written about concepts like interleaving and sequencing in sciences and maths but very little that I have found about how these concepts may apply in biology teaching.

Specifically, I have written up some of my thoughts on sequencing my DP biology curriculum based  on these discussions here.

Some of what I have learned suggests that solid conceptual/abstract understanding can only be developed when novice learners have embedded factual or propositional knowledge in their own mental schemas. In addition, I have tried to think about how principles from cognitive load theory may apply in terms of biology teaching and the sequencing of content.

One example of this has been how I approached the teaching of the concept of natural selection this year for my Y12/G11 mixed SL/HL IB biology class. In the IBDP biology syllabus, this is topic 5.2 and I sequence it after 5.1 “Evidence for evolution” and before 1.5 “The origin of cells”.

I finish the evidence for evolution section by looking at the peppered moth and the changes within the populations studied by Dr Ketterwell, through this online simulation.

In the past, I have taught natural selection by going over the concept of natural selection and then looking at specific examples of it that are mentioned in the syllabus which are antibiotic resistance in bacteria and changes in the beaks of the finches of the Galapagos island of Daphne Major.

This year I sequenced the topic into three lessons (which unintentionally appear to have been interleaved as we are also doing the internal assessment at this point in time and one lesson a week is given over to just the HL students anyway) and taught specific examples of natural selection before finally generalising from these examples to the abstract concept of natural selection.

Lesson 1 – Antibiotic-resistant bacteria

We started with retrieval practice of previous material using a google slide presentation which contained four questions: one using material from the last lesson; another from last week; another from last month and another from the last term. I then asked the students to draw and label a prokaryotic cell. Something that they covered six months ago.

Once completed we moved on to watch some news reports about antibiotic-resistant infections and I asked students to discuss and articulate back to the class what they thought the key message of each of the videos were. These prompted discussion about the general nature of antibiotic resistant bacteria and I used questioning to continue this discussion amongst the class. We also discussed what antibiotics were and why they were used to treat bacterial infections as this was a concept we met when studying the immune system two weeks prior. I highlighted the possible area of confusion for students between the words antibiotic and antibody which I had picked up from examining the previous May session of exams, before going on to explain how bacteria have become resistant to antibiotics.

I then gave the class a past paper question to complete the topic and we reviewed the key points of this question from the mark scheme.

Lesson 2- Finch beak changes on Daphne Major

Again we started with retrieval practice in the same format as in lesson 1. We then conducted a physical simulation as outlined in this practical, where students mimic being finches and collecting food. This was followed by a discussion of the trends we found in the simulation and what this might tell us about birds collecting food in the wild.

We then moved onto exercise 3 from this page and when students had finished the video and quiz I asked them to summarise what happened to the finches in the film.

Lesson 3 – the concept of natural selection

After retrieval practice, we reviewed the definition of evolution we had covered in 5.1 “evidence for evolution” and I highlighted that natural selection was a mechanism by which evolution could occur. I then asked students to think back and name the three examples of natural selection that we had considered in the last few lessons. Once they had written their answers down, I went through those examples and placed them on the board. I then asked students to discuss in pairs the details of each of these examples, before snowballing into a class discussion of the details of each of the three examples: peppered moths, antibiotic-resistant bacteria and changes in finch beaks. While we discussed these I wrote down the key points from each one on a second board with each example in a column so that similar elements from each example ended up in the same row. I then discussed with the students what these key features of each of the examples were and related this to the concept of natural selection. We finished with an example question asking students to describe the process of natural selection using examples.

Biology EAL Resources

General Bio EAL teaching resources

Quizlet deck of 100+ suffixes and prefixes

Suffixes and Prefix list supplied from comments in this post

Suffixes and Prefix list supplied by Gretel vB

IBDP Bio Reources