This Week in the Classroom: What Do Plants Eat? And How Does It Grow Leaves? And Other Teaching Errors

What exactly, is a plant’s food?  And where do the raw elements that make up a tree trunk come from?  Take a moment and think up two answers.

I had a student ask these questions on a recent field trip.  The answer given by the speaking biologist to the second question was wrong.  In fact, I’m willing to bet your second answer was wrong too.  Plants convert sunlight into energy, which is analogous to an animal eating sugar.  Then where do the raw elements for cellulose (the stuff in a plant’s cell wall) come from?  Not the soil, as you probably answered.  A plant breaks down carbon dioxide (the air)  to create the cellulose in the cell walls (its formula is C6H10O5….nothing there about silica or iron or calcium or what-have-you).  That oak in your front yard?  It’s air and water chopped up in a blender and squished out like sausage.

A teacher faces an enormous pressure in the classroom to “get it right”, whether they teach math, science or woodshop.  English teachers are expected to write good.  That pressure comes from an expectation on ourselves, our students, the culture of teaching and from our parents – but sometimes, in the give and take of class discussions, we get the answer wrong. Usually we know better, sometimes the correct answer (for example, is there gravity in space? Or, can an object be in motion without a force acting upon it?) isn’t always the “common sense” answer.  And sometimes, the subject we teach happens to be a political minefield, and the “right” answer becomes a little less obvious.

We don’t always have to get it “exactly” right. A teacher can admit mistakes.  Nor does a teacher need to believe in being infallible – there can always be room for another interpretation of a poem, or the squishiness of real-life measurements versus theoretical computations or a different technique for sawing a board.  But if nothing is truly correct, then why even study a subject or care about getting the answer right?

This can happen in a scientific setting too.  My high school biology teacher didn’t begin his course with cell walls and cellulose, he began with an explanation on how scientific thought & terminology worked.  He launched into evolution with a  statement similar to this: “Regardless of your, or my, personal views on creation, this is a scientific course.  I will explain biology to the best of my ability using best the tools and framework science currently has – and that is Darwin’s theory of evolution through natural selection.  I don’t intend to change your hearts and minds and I won’t engage in a debate out it.  This is a biology course and the answers, for the purpose of our time here, can be found in within current accepted scientific thought.  I ask you to respect that.”

I appreciated that statement as a student.  I appreciate it a lot more as a teacher.  He allowed my own opinions to be validated, if necessary.  He then asked me to respect his position as a teacher, which I did to the best of my ability.  He neatly side-stepped a minefield by phrasing his knowledge as part of a larger continuum.  He asked his students not to change their minds, but be open to a different way of thinking and engaging the world.  It’s a similar frame-shift necessary to see the value of Freudian psychology or analyze literature through the lens of a different culture.  I think many of the “culture-wars” which happen in the classroom occur in part because teachers forget to explicitly state what we are actually doing: asking the student to think critically about the subject with an open-mind and to approach it with a sense of belief in the subject.  The student doesn’t need to ask “why even read poetry?” to try to answer “what can I learn from this poem?”

Back to mistaken knowledge in the classroom – my point here has little to do with the evolution-creationism debate, but more to do with how a teacher can allow for factual error or differing opinions about controversial subjects.  My biology teacher allowed for differing opinions while still engaging his subject matter.  As I wrote about in this post, I had to re-teach a basic skill I thought my students had mastered.  Or an English teacher can simply admit “I have no clue what Shakespeare is talking about in this monologue, what do you think?”

As a teacher I don’t try to avoid factual errors and controversy, because I don’t think I ever really will, but to avoid those things becoming roadblocks in my students learning and my teaching.  Students, especially students which exhibit very rigid-thinking, tend to see the classroom as a black-and-white world.  You get the answer right or not.  The bubble is filled or it isn’t.  Errors and controversy become roadblocks for some students.  By recognizing mistakes and controversy, I ease those students into a different frame of mind.  By allowing the concept of error a place in my classroom, I believe I create a richer, more nuanced environment for my students – I hope you do to.

Make it safe and keep the rubber side down.