Looking through this summer's M'22 exam papers I wonder if my student's missed anything during their course. In IB speak you could call this teacher 'reflection time'. Of course there are always some questions where students are expected to engage with novel Biology using knowledge and understanding from the DP course, but I mostly worry about those questions where the answer is simple, but seems complex, or those corners of the DP Biology guide, like autoradiography, which could be addressed with more or less detail.

Here are a few changes I might give to my next DP Biology class:

• Find more opportunities to look at the consequences of all biological  the properties of molecules, to ask, "So what?".  Lots of multiple choice questions go beyond factual recal into consequences. e.g. Q5 on HL paper 1. The question requires a knowledge that glucose is a polar molecule, and thus soluble in water, but the question asks, "Which features allow glucose to be transported in blood plasma?" Asking, "So what? Why is it important that glucose is soluble in water?" in lessons will better prepare students for these "consequences multiple choice questions", even if it drives them mad in class!
   
• Practice deducing things from graphs. Q2 and Q21 in the HL paper 1 are examples of how you can check whether students understand using a graph and a few statements. Diagnositic question style could work well here, "How confident are you that this statement is true or false?"
  
  Here's an example, notice that it's not the graph you expect, of lung volume over time.

  Testing student understanding of graphs using diagnostic questions.

  The graph shows the pressure in the lungs during light 'tidal' breathing.

  Choose one of the following responses for each of the statements below:

  • I'm sure it's correct
  • I think it's correct
  • I think it's wrong
  • I'm sure it's wrong
     

  1) At X there is no air movement in the trachea.

  2) At point Y the external intercostal muscles are contracting.

  3) The Diaphragm is fully relaxed at X.

  4) The rate of breathing is 0.4 breaths per second.

  ---

  1) At X there is no air movement in the trachea. 

  This is wrong. At the highest thorax pressure there will be the fastest rate of expiration.
  There is a moment when there is no air flow in the trachea when the thorax pressure is equal to air pressure.

  2) At point Y the external intercostal muscles are contracting.

  This is wrong, the external intercostal muscles only contract during inhalation.
  When the black curve is above the blue Air pressure line exhalation is happening.

  3) The Diaphragm is fully relaxed at X.

  This is correct. Abdomen muscles are pushing the diaphragm upwards, so it is relaxed.

  4) The rate of breathing is 0.4 breaths per second.

  This is almost correct, there are approximately 4 breaths in 10 seconds which equals 0.4 breaths per second.
  More precisely it looks like 4 breaths takes a little more than 10 seconds, perhaps as many as 11 seconds.

• Keep cholesterol explanations simple. Q3 in HL paper 1 is tricky for students who know too much because it mentions temperature. The role of cholesterol in membranes is temperature dependent, but the DP guide gives a simple statement, "Application: Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes." A bright students may have read that, as the temperature rises cholesterol reduces membrane fluidity by increasing intermolecular forces. Which will help them to get the correct answer, but they may also have read, "When the temperature drops, cholesterol increases fluidity by keeping phospholipids from packing closely together." Knowing this makes the question more complex.
   
• Link ribbon style protein diagrams to dipeptide and polypeptide diagrams.  Q6 in the HL paper 1 shows a ribbon style protein diagram with the amine group on one end. We all know that the other end of the polypeptide chain will have a carboxyl group, but do we think of it when viewing a ribbon diagram?
   
• Look at different methods of animal cloning.  The DP guide states, "Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells." and "Methods have been developed for cloning adult animals using differentiated cells." and "Application: Production of cloned embryos produced by somatic-cell nuclear transfer." I usually skip quickly to the somatic cell nuclear transfer. Perhaps the basic idea, that embryonic stem cells can be broken into more than one group of cells, as illustrated in Q13 of HL paper 1, merits more time.
   
• Use specific examples with long biological names in lessons.  Many multiple choice questions use specific biological names that do not need to be understood to successfully answer the exam question. E.g. Q12, "Hemochromatisis", Q19, "Saphylococcus aureus" & Q28, "E.coli ribulonuclease HI" and Q37, "cetuximab". If students have never had to negotiate these long names before the exam they may be less confident about their understanding. If students realise for themselves during lessons that long biological names are just that, long biological names, it will help their confidence when they read them in the exam.

Diagnostic questions

Diagnostic Questions are a quick way of assessing student knowledge and understanding. Asking, "How confident are you?", then asking for a justification why the student thinks the statement is right or wrong, we create opportunities for students to explain their reasoning. The answers are no longer right or wrong, as so often in Biology, and the justifications reveal the level of understanding, or misunderstanding.  Student misconceptions are revealed given students time to correct them. The student has to engage with the question to offer an opinion, which has the added effect of increasing participation.

For example a factual question like, "What is the function of these valves in this fish heart?" has one answer and either students know it or they don't. Those that don't know will keep quiet.

A diagnostic question would be something like,

Choose one of the following responses to summarise your reaction to this statement: 
Both of the valves are essential if the heart is to pump the blood around the fish's body.

• I'm sure it's correct
• I think it's correct
• I think it's wrong
• I'm sure it's wrong

Everyone can participate at the first stage. A student who thinks that it is wrong will then have a chance to explain why, giving the teacher and the student the opportunity to identify any misconceptions that they may have, providing meaningful Assessment for Learning (AfL).  The best statements include an element of doubt. A statement like, "The valves prevent the blood flowing backwards." will generate much less discussion.

To find out more about diagnositic questioning, read this paper, Approaches using Diagnostic Questions from York University Department of Education.