Reframing Biology

biologyIt’s a perennial discussion… in what order do you teach the biology units.

Like many of you, when I started teaching AP Biology years ago I organized it by domains of scale:

  • The Domain of BioMolecules
  • The Domain of Cells
  • The Domain of Organisms
  • The Domain of Populations
  • The Domain of Communities & Ecosystems

I did it that way because I was taught that way and the textbooks were organized that way. But I became disenchanted with it because I felt like I was merely marching through the material instead of making connections between domains. So I started mixing it up — teaching principles and then teaching a unit that highlights a body’s application of that principle (form and function) — like teaching osmosis and then teaching kidney function as an example of osmosis.

But over the last couple of years, I have been brewing on a re-framing of the course that takes this idea further. I have started to view the material as being divided up between (1) large-scale interactions and (2) cellular processes.

Under LARGE-SCALE interactions I place evolution and ecology, because these are built on long term processes or interactions between organisms or groups of organisms. And I start my course with these because (1) evolution is my guiding principle for the rest of the year and (2) interactions between organisms and populations are easier for students to grasp this early in the year of their intellectual development.

SideNote: Many people have asked me how I teach evolution before teaching genetics. That always makes me laugh because if you think about it, Darwin developed the principles of evolution by natural selection without having been taught genetics himself!

I teach evolution before genetics, because you don’t have to know the nitty gritty of genetics to understand evolution. You only have to know that inheritance happens — and every high school kid knows that s/he looks like one or other of their parents.

Specifically for population genetics, you get to introduce/review some concepts and vocab early on in the course this way too, like you can introduce them to allele, heterozygote, homozygote… but each can be explained in one sentence and I consider that an advantage instead of a disadvantage.
I leave evolution by segueing from speciation into phylogenetics/taxonomy (who has evolved on this earth) and then into ecology (how they all interact).

Then I introduce CELLULAR PROCESSES by discussing that organisms are coordinated masses of cells that must perform a set of shared tasks. And I now organize this unit within the framework that cells have 3 main jobs: (1) to make energy, (2) to make more cells, (3) to make proteins. And for me everything else in the course falls under those functions.

First you have to discuss cell structure to lay the foundation — that includes biomolecules & their behavior, cell organelles, cell membrane, and movement across the membrane. Then we discuss making energy and all the animal & plant systems that have evolved to support that in one way or another:

    • Respiration
      • Digestion — taking in fuel
      • Gas exchange — taking in O2 & releasing CO2
      • Circulation — moving raw materials to & wastes from cells
      • Excretion — removing intracellular waste
      • Immune System — protecting an interconnected mass of cells & tissues
      • Motor System — using the energy produced in respiration
      • Nervous & Endocrine Systems — coordinating an interconnected mass of cells & tissues to make it an organism
    • Photosynthesis
      • Gas exchange — taking in CO2 & releasing O2
      • Plant Structure & Growth — highlighting the differences & similarities between plants & animals but how each structure supports making energy or using products

Then we discuss making new cells both for asexual reproduction and for the special case of sexual reproduction & all that extends from those topics:

    • Mitosis
      • DNA replication
    • Meiosis
      • Genetics

Then we discuss making proteins & that opens the topics that have come from the new DNA-centric world that we live in:

    • Protein Synthesis — transcription & translation
      • Gene Regulation
      • Biotechnology

And that’s where I end the course.

I hope this offers you another perspective than the one dictated by your textbook. I strongly believe that students get a more integrated view of the biological world this way. I feel like it tells a story that both holds their attention and makes sense, rather than marching through a mass of vocabulary as if we are teaching a foreign language.

Maybe someday there will be a textbook that breaks the mold of domains of scale.

Kim Foglia

Kim Foglia

1 Comment »

  • kmurray81 says:

    Kim, I teach biology on a semester basis. This year I wanted to teach photosynthesis around the same time the leaves start to pop (a few short weeks away!!!) but a colleague advised me to stick to the sequence he (or “we”) developed. I have dealt with a similar argument when teaching geology, where do you start plate tectonics or types of rocks/minerals?

    Your post has helped me develop my argument for breaking the scripted sequence we have developed. Also, I think as long as your lessons connect and a sequence is developed, and shared with your students, connections will be made and the content will be mastered.

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