How many biology courses begin with cells? Most Year 7 courses (11 years old) begin with cells. Then at 14 years old GCSE biology courses begin with cells, and when they move on to IB or A-level biology (when 16 years old) we have cells again. Why do courses stipulate this? Of course the answer is that life is based around cells. We have cell theory for a reason; what elements are to the chemist, a cell is to the biologist. The indivisible unit. But does this lead to good learning. Looking from pedagogical, rather than a subject knowledge, perspective, why is is good to start with cells and their constituent organelles?
Imagine the level of abstraction when suddenly beginning a new biology course and we present a picture of a cell with all these labelled parts, often including their abstract roles. I wonder here, what is the purpose of learning these organelles at this point? From the students point of view, they could clearly ask: why are we learning this? Some students won't do this, as they clearly revel in scientific abstraction and facts. But others may be asking this silently. At best we could reply that cells are the basic units of life, etc, and that this knowledge will link into later topics, etc. At worst we could reply that, as it is on the exam, they will need to know it. I worry about how this shapes our students' view of biology as a science. Could it further instil the idea of biology as merely a science of jargon, vocabulary, and classification?
The premise of cell theory is rather simple and it is important for students to know the central importance of cells to life, but when do they need the details? I would argue that the details should be taught with purpose, to create Ausubel's meaningful learning, in that when we teach organelles and their roles they are grounded in meaning; the learning is linked and stored in a larger scheme in the long-term memory.
Instead of students drawing a eukaryotic cell with all its organelles in the first few weeks, what if cell organelles (or at least some) were introduced over time within units of learning that require their presence. Students construct their mental model of the cell alongside the processes that they carry out. Eventually students could draw a cell just like any other student, but maybe with more meaning, possibly with more knowledge linked to what they draw. It would also have the advantage of allowing students to link the processes more easily to the higher levels of organisation. Here's a few examples of how this could be done for an IB biology level course:
Centrioles: introduced with mitosis (& cancer)
Endomembrane system (ER & Golgi): introduced while learning about exocrine glands (in the digestive system, for example)
Ribosomes & nucleus details: introduced during transcription and translation
Mitochondria: introduced with learning of cellular respiration
Chloroplasts: introduced with learning of photosynthesis
Membrane: introduced while studying the intestinal epithelium
Lysosome: introduced alongside phagocytes
Cytoskeleton: introduced with any cell that has microvilli
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Christian Moore-Anderson
@CMooreAnderson (twitter)