I am going to take a break from writing about tame topics like pipelines and Site C to try my hand at a truly contentious topic: teaching evolution in the BC classroom.
As any Grade 7 teacher (or Grade 6 if you are doing A/B Year Schedules) knows, the new BC curriculum has made the topic of Evolution one of the “Big Ideas” for Grade 7 Science. Needless to say a lot of teachers have not had to teach the subject before and are at a loss how to address many of the challenges associated with this potentially hot-button topic; especially given the age of the children being taught. As a practicing scientist, I do a lot of science outreach in the schools and this year my wife asked me to come down to her school to help a couple of her colleagues who were looking for assistance teaching the subject to their students. In this post I would like to share some ideas I have gleaned on how to make this challenging topic understandable for elementary-aged kids and to avoid/side-step some of the landmines associated with teaching this topic.
The BC Curriculum Guide breaks down the topic into three areas:
- changes in traits over time,
- survival needs, and
- natural selection.
The problem is that these are not intuitive divisions so I will give some simple ideas about important topics you may wish to cover.
What’s DNA? – let’s talk LEGO
In order to really understand evolution kids need a basic understanding of the concept of DNA. The problem is DNA is not an easy topic to teach or understand in Grade 7. When I was in high school we were taught the DNA was like a recipe book. Follow the recipe right and you make a living creature. Make a mistake following your recipe and you might have a delight or a disaster.
While that may fly for older kids, for younger kids I find that teaching DNA using LEGO is a better analogy. Think of DNA as the instruction booklets that come with a set of LEGO and the bricks as the proteins etc.. that make up a cell/body. Since my son is a LEGO fan I use a Super-Star Destroyer as an example. It comes with multiple little books and multiple little bags of parts. Using the books you assemble the parts. Because the project is large the chance exists for a mutation where one brick is put in the wrong spot. It might be 15 steps later before you discover that the error (a mutation) means another brick can’t be placed where it is supposed to go. Maybe your saucer unit won’t fit on the top and you have to move it. The change may be good or bad but it is a change. If you are lucky the change makes your LEGO creation cooler and not a disaster. It you are unlucky your Super-Star Destroyer loses its sensor array and the Millennium Falcon sneaks up behind it and blows it up.
Natural Selection – Mold and bacteria fight it out
Building on the idea of DNA we can talk about natural selection. To introduce the topic I like to talk molds and bacteria. I use molds because every kid has seen moldy bread and we all know about bacterial infections. I explain how mold and bacteria have been at war since forever (fighting over the surface of an old rotten orange as an example). There is only so much orange to go around and so the slow-growing mold really have to work hard to beat the fast-growing bacteria. I explain how one lucky penicillium had a mutation that caused it to make a protein called penicillin. This protein killed bacteria and because it did the lone penicillium was able to reproduce and win in its battle against the bacteria and take over the orange. Because of its success it was able to reproduce and now kitchens everywhere have penicillin producing mold ready to eat old, stale bread.
Given your time availability you can then segue over to the idea of antibiotic resistance as that goes back to the idea of survival needs and the need to adapt to survive.
Natural Selection – Survival of the fittest
This is a relatively easy topic. Most kids have seen documentaries where the pack of wolves/lions stalk a herd of prey animals, identify the weakest member of the herd and attack it. In this scenario the weak are killed and the strong get away to have kids.
The other side of the coin can also be interesting for kids. Many of the kids at our school fish and crab and many have measured crabs and thrown back the little ones. I point out how that throwing back the little ones means that the little ones may actually be fitter in that case. Fitter doesn’t always have to be bigger just more likely to make it to the next generation.
Adaptive Radiation- Dump the finches let’s talk dogs
Having talked about natural selection we can talk about the idea of adaptive radiation: how organisms diversify from an ancestral species. Darwin has his eureka moment by looking at finches in the Galapagos and since that time science teachers have used that model to teach their students, to great boredom. Little brown birds are exciting to bird lovers like me but bore my kids to death. What my kids do love is dogs and dogs are a great way to introduce the topic of adaptive radiation.
I ask the students to identify the dogs they have and then go from there. In one class we had two boys, both with chihuahuas, and I asked if they imagine 100,000 years ago whether packs of chihuahuas roamed the plains taking down buffalo. We all agreed that this was likely not the case. I explained that when the first wolves decided that being friends with humans was a better way to get a meal than trying to eat humans they looked nothing like the dogs of today. Our ancestors bred dogs based on traits and we ended up with the breeds we have today. I then provided some typical traits we have bred for: protection – mastiffs; ability to catch vermin – terriers; ability to fetch downed wild fowl – retrievers etc.. This provides an easy to understand example of the essence of adaptive radiation. It also help because so many families have new mixed-breeds like the Labradoodle.
A Common Ancestor – No we didn’t evolve from apes, think more like long-lost cousins
Eventually every class has to deal with the common ancestor problem. Now we all know that we have a common ancestor because DNA is a pretty complicated way to keep track of your proteins and we all have DNA. But how do you explain that to kids. The best way I have found is to talk about families. I have brothers and they have kids. My kids therefore have cousins. My kids are not descended from their cousins they are descended from a common ancestor (their grandparents). Extrapolate backwards and we can infer that everything with DNA must radiate back to to a common ancestor. Moving downwards we come to recognize that we are all related but may not be descended from each other.
About that whole religion thing
The part of teaching Evolution that really had our teachers on edge was the fact we live in a very religious community with adherents of lots of faiths and the teachers really want to avoid stepping on religious toes. While teaching evolution will anger some parents it can be done in a way that reduces the likelihood of negative feedback. As a first step it is important to point out that everyone has their own way to look at the world and no one way is necessarily better than another.
Science is one way in which many people look at the world. As I scientist I was taught the scientific method. An individual sees something; makes a hypothesis; collects data against which to test the hypothesis; and revises or discards the hypothesis based on the information collected. The process is iterative. Do this enough times and the hypothesis becomes more robust (a Theory) and maybe given enough time it becomes a Law. Scientists being conservative will often call a well-tested theory a “Theory” long after it really should be called a Law. Such is the case with Evolution. Science has done enough work to demonstrate that evolution happens and we even understand, to a great extent, how it happens. Does this, therefore mean that evolution contradicts religious teaching? I don’t think it has to in the elementary classroom.
It is important to point out that at this current place in time, science doesn’t have all the answers. We still don’t have a handle on consciousness and while the basics of evolution are in place we are still ironing out how that first life went from connecting naturally occurring proteins to forming simple organic molecules to a functioning nucleus with self-replicating DNA. This provides a lot of wiggle-room for the elementary-level educator.
To help understand I have previously explained the topic this way. I was brought up in the Catholic tradition and in the Catholic tradition the original bible was written in Hebrew, Aramaic and Greek with the Genesis story written in ancient Aramaic. Ancient Aramaic and ancient Hebrew were languages that had limited vocabularies and as such the Genesis story would be similarly limited in how it could explain the origins of humanity. As an example, neither ancient Aramaic nor ancient Hebrew have words for really big numbers (like a billion) and they certainly don’t have language to describe an accretion disk coalescing to form a planet. As such the language used in the Bible is necessarily simplified. A “day” in Genesis could mean anything from a solar day to a billion years and as such evolution doesn’t have to contradict your students’ religious heritage. Rather evolution can snuggle up in that gray zone that gets the lesson taught and avoids lots of angry letters/phone calls from parents.
Now I apologize in that I tried to fit a lot into a single post and so a lot of detail is missing. I gave two presentations this week and each took about an hour of which at least 20 mins was kids asking questions and teachers clarifying details that they (or their students) were not clear on. Given our school (we live in a very religious community) and the fact that last night was meet the teacher, I expected my wife to relay some parental feedback from the classes I visited, but I have yet to get any. That is a good thing in my books.