Progression in science

Match making in science: the importance of understanding progression

What is it that great science teachers do? Do they enthral students with stinks and bangs? Do they tell exciting stories of past scientific discoveries? Do they inspire curiosity through imaginative inquiry and practical work? Or do they ‘just’ make sense? I say ‘just’ but we all know that making any class understand the abstract world of science is not an easy task as learning science is hard!

For science to make sense the science teacher must correctly match the activity, explanations, questions and scientific concepts to be taught to the students in front of them.

Some might call this ‘matching’ differentiation, but I think it goes beyond that. It’s about reading your class and making a decision as to what’s the best strategies and narrative to use at a particular moment in time, to help a specific group of students understand a scientific concept. This doesn’t mean that every student will require a bespoke teaching programme. But it does require the teacher to have a detailed knowledge of progression, so that lessons can be planned and adjusted in response to the needs of the students in their class.

Distinguish between the cause and the symptom in lesson feedback

Too often science teachers are criticised for poor questioning, pitch or planning when in fact the issue lies with progression and content knowledge; the difference between a symptom and the cause. Without a strong progression model it is difficult for teachers to stretch or support students, plan lessons and check understanding. It’s crucial that we can articulate exactly what knowledge and understanding underpins the larger scientific concept we are trying to teach. Let me try and explain the importance of understanding progression in the context of electrolysis – the splitting apart of a compound into its elements using electricity.

Progression of ideas in electrolysis

Imagine I wanted to teach Year 10 students about the electrolysis of lead bromide. To be successful in this topic students could know the following:

  • Lead bromide is a compound because it is made from different elements joined together
  • The chemical formula is PbBr2
  • It is made from lead and bromide ions
  • Lead ions are atoms that have lost two electrons
  • Bromide ions are atoms that have gained one electron
  • We need two bromide ions for every lead ion. This is why the formula is PbBr2.
  • Lead bromide forms a giant ionic lattice
  • When we heat lead bromide it becomes a liquid
  • Because we break many ionic bonds
  • The ions are free to move in a liquid
  • Current is the flow of charge
  • A molten liquid will conduct electricity
  • A wire is made of metal
  • Electrons are delocalised in metals and are free to move so can conduct electricity
  • If we connect wires to a battery current will flow but if there is a gap then the circuit will be broken
  • Graphite conducts electricity
  • Because carbon atoms form only three bonds and so there is a spare, unbounded electron for each carbon atom that can move
  • We can use these conductors along with molten lead bromide to create a circuit that will conduct electricity
  • Lead ions move to the negative terminal and gain electrons forming lead metal.
  • This is called reduction.
  • Bromide ions move to the positive terminal and lose electrons forming bromine gas
  • This is called oxidation
  • We can represent oxidation and reduction using half equations
  • Two bromine atoms join together by a covalent bond forming brown bromine gas.

Now we have articulated the progression of ideas in the electrolysis of lead bromide, we can begin to perform some important matches so that our narrative i.e. our lesson, makes sense.

  1. Match the knowledge from the progression map to your class i.e. what knowledge can your class be successful at understanding? What knowledge is fundamental (my ideas indicated in green) to understanding electrolysis? What knowledge is helpful and what knowledge is superfluous but a useful extension for preparing students for A Level?
  2. Match the activity type to the knowledge and class you are teaching i.e. what type of activity best teaches students the difference between an atom and an ion? Is it role play, worksheet, model etc? What does the research say? And how can you adapt published resources to your class?
  3. Match your questions to the progression map and then to your students e.g. what questions will you ask, in what order and to whom?

How can we match better?

So, how can we become better match makers, so that more lessons make more sense to more students? I think we need to start with a clear understanding of the scientific concepts we are teaching and know how they progress, both within the lesson and overtime. We must understand that elaboration of one idea in science depends on an earlier idea being understood and so ascertaining prior knowledge is key. We must identify the fundamental, helpful and extending knowledge. We can then select resources and adapt them for our classes, both before and during the lesson, so that all students can gain pleasure in learning and understanding the same key concepts but to differing degrees of completeness. And finally, we need to try hard to make learning visible, through well selected activities that challenge students at key points along the progression map; when students don’t understand we/they must make adjustments so that match making can continue.

Further reading