Models (14–16): Plants
Plants: a topic loved by many teachers (and me), but loathed by many students. My goal is to invite students into my joy. That involves, as I argue in Biology Made Real, starting with the whole plant and learning about its trying to do. Without this, students can’t connect the parts they learn to the plants they experience.
The nature of plants
This lesson is an example I gave in Biology Made Real. It begins the topic by distinguishing autotrophy from heterotrophy. This firmly establishes a way of being for plants: how they sustain their autopoiesis. All other things students will learn in the topic will have a function, and biological function is always in relation to how it sustains the whole. In this lesson, I employ the essential move of varying to make meaning of plant autotrophy. To do this, we compare with parasitic plants who are not autotrophic. Read about varying as an essential teaching move in Teaching Meaning.
CSR theory
I’m yet to see CSR theory appear on standardised exams, but I teach it at every stage, 11–14, 14–16, and 16–18, precisely because it gives so much meaning. As I explain in Biology Made Real, it’s a theory of the whole organism and its way of being: it allows students to observe plants in their environments and deduce what they’re trying to do. In turn, this also allows students to deduce what the environment must be like. And students can do all this by simply observing things like their leaf and stem types and how many flowers they have. For this lesson, I typically take students to a patch of natural land near the school where we can touch the leaves and compare plant forms. If this isn’t possible, I bring examples into the classroom.
Plant cells
Having gained a feel for the whole plant in the previous lessons, it’s time to look at its parts and how they contribute to this way of being. Using the essential move of varying, I compare plant cells with other cell forms.
Photosynthesis and respiration
I explain this lesson in this post.
Leaf structure
This is a lesson that lends itself well to both a structural diagram and a stock and flow model to summarise a set of relations. The essential teaching move of varying can be used widely. For example, we can ask, “What if the palisade cells lay horizontal instead of vertical?”. I explain this lesson in Difference Maker.
Vascual tissue in plants
This is a simple lesson looking at tissues and relating them to their function. We also have a lesson with microscopes looking at xylem in banana peel and stomata in tradescantia leaves.
Transpiration
Transpiration is another topic that lends itself perfectly to a stock and flow diagram to summarise a set of relations, with which students can make predictions. I designed the stock and flow structure to represent the typical flow direction of water (these design features make a big difference for students). Stock and flow models also invite co-construction like no other form of diagram. Firstly, we draw the diagram showing the transpiration pull, and I make explicit the key distinctions of the pull, evaporation, and diffusion. As students are now well-versed in diffusion and its patterns, we can then co-construct the stock and flow diagram. See how to co-construct these models in Difference Maker.
Planning a transpiration experiment
When we plan or discuss experiments, we use a diagram I invented that invites sense-making and co-construction. Read about these diagrams here. I present the results of this experiment in the graph below.
Learn how to teach this way in my books:
