Tree of life

One of the easiest and most elegant ways of explaining the classification of organisms, the history of life on Earth, and the relationships between different organisms is to construct a phylogenetic tree. I have a great exercise I like that takes just some bits of colored paper, string, a poster board and some thumbtacks.

To start, each student writes the Latin domain, kingdom, phylum, class, order, family, genus and species names on separate pieces of colored paper. I hand out paper in stacks and give them strict instructions not to rearrange the order of the colors. Wikipedia is actually a great resource for this because they tend to be quite reliable on this if they have the specie you’re looking for (and they have quite a bit).

Students then tape the pieces of paper together on a string, species at the bottom, domain at the top, and, one by one, tack them to the poster board. As each student attaches their string to the board they say the common name of their organism and then recite the phylogeny.

When I did the exercise on Monday, I asked the students to use the organisms they’re working on for their independent research projects so everything started with the domain Eukaria. Interestingly enough, the Wikipedia pages don’t have the domain classification, probably because they think it’s too obvious, but I had a number of kids spend quite a bit of time trying to figure it out; they probably benefited from doing so I didn’t mind at all.

phylogenetic-tree-100 — Constructing the phylogenetic tree.

Classifications that are the same are tacked one on top of the other, Eukaria on top of Eukaria, Mammalia on top of Mammalia and so on, so that, as students add their parts of the phylogeny, you begin to see the phylogenetic tree. We had insects, mammals, plants and reptiles, so there was quite a nice variety represented.

After about half a dozen lineages were on the board, the procedure began to get a bit repetitive, so I started to ask students to guess, based on the common name, where the next species to go on would diverge from the rest of the emerging tree. Students seemed to like this part of it. I had started with homo sapiens when I demonstrated the procedure so it was salutary for them to see how much the other organisms differed from humans.

When everything is tacked on, you end up with a cute picture of a the tree of life that makes a cute, but awfully real looking, phylogenetic tree. Students tack their pieces of paper on the string at different distances, some much closer together than others. As a result, the final tree is looks as though it shows the genetic divergence between the different groups. It a fake, but lends a sense of verisimilitude non the less.

Committees

We’ve discovered committees. Yesterday, after spending half an hour discussing the brand new bread bag prototype that one of the students came up with, they decided that maybe just the people interested in working on them should work on them. So we just, organically, created a committee.

As with all new discoveries we’re now using them for everything. Today the students decided on a committee to run Dinner and a Show. We’ll see where this goes.

Writing good paragraphs and essays

WritingDEN‘s Tips-O-Matic is a great site on writing great paragraphs and essays. The pages are very simple and well organized, without all the distracting noise of ads and extraneous information.

The language curriculum focuses, in general, on developing good writing style and craft, but some of my students need to work on the basics of essays a bit more, particularly with high-school entrance essays coming up.

What’s the difference between humans and animals?

In the field of cognition, the march towards continuity between human and animal has been inexorable — one misconduct case won’t make a difference. True, humanity never runs out of claims of what sets it apart, but it is a rare uniqueness claim that holds up for over a decade. This is why we don’t hear anymore that only humans make tools, imitate, think ahead, have culture, are self-aware, or adopt another’s point of view. – Frans De Waal (2010).

My students studied the question, what is life, last cycle, and through their readings and Socratic dialogue I’ve been trying to approach the question of what is sentience and what distinguishes humanity from other organisms (or robots for that matter).

We’ve found that the lines between us and them are very hard to draw.

Pushing the discussion into questions of morality, primatologist Frans De Waal has a wonderful post on where it comes from, and if there is any clear distinction between humans and other animals. He argues that morality is innate, a product of evolution, and there aren’t clear distinctions.

The full article is a worthy read, with good writing and well constructed arguments. It’s a bit too long for a Socratic Dialogue but might be of interest to the more advanced student, particularly those going through religious, coming-of-age, rites of passage, like preparations for confirmations and Bar Mitzvahs. While De Waal’s evolutionary reasoning has been used to argue against religion, he takes a much more subtle approach:

Our societies are steeped in it: everything we have accomplished over the centuries, even science, developed either hand in hand with or in opposition to religion, but never separately. It is impossible to know what morality would look like without religion. It would require a visit to a human culture that is not now and never was religious. That such cultures do not exist should give us pause. – Frans De Waal (2010).

Memories in the fire

1

I decided that we would read our memoirs, the ones my students had been working on for the last five weeks, on our immersion trip down to Mississippi. The idea of sitting around the fire, sharing memories was just too enticing to pass up.

I was a little surprised that no one objected, or even hesitated, when I made the suggestion the week before. We’d just come in from soccer and I was trying to figure out how we’d fit the projects, the tests and the presentations into the time we had left. There was a precedent. They’d read their first stories, the ones from the orientation cycle, on our first immersion and that had worked out well because it had given us an entire afternoon to have a great discussion. They seem actually to look forward to, what’s come to be called, “Teatime with Doctor.”

“What if,” I asked, a little quietly to one of the 8th graders, who’d been on the challenge course immersion the year before and happened to be walking by, “you read your memoirs around the campfire on immersion?”

“Yes.” Declarative and succinct. I raised an eyebrow, but he just continued on his way. I was a little surprised he did not have more to say. I’m always surprised when my students don’t have more to say. My students can be quite loquacious given any opportunity, and this one in particular tended to have strong opinions that he was usually more that willing to share.

The discussion with the rest of the class took barely longer. The larger the group, the more likely you are to have people who need to think out loud, but there were unanimous thumbs up in less than two minutes.

I think that there’s some primal need that gets stirred up by even the thought of sitting around a fire and sharing stories. Of course this plan of action also fulfilled that other fundamental need of the adolescent, the need to procrastinate.

II

We get to Camp H., have lunch, and an afternoon of community building games. Lamplighter’s been working with the camp leader here for years and Ms. A’s impressed by how well this group works together. No surreptitious sabotage, no subtle denigration, no stubborn unwillingness to participate.

We talk about the group, she and I, as we walk back to the cabin, red gravel crunching under our feet, oak leaves turning color overhead, and myself getting slightly out of breath on the last climb. I’m perhaps a little more impressed than she is because I can see the conflict in those by now familiar faces; glimpses of of baser instincts being overruled by the prefrontal cortex. It is a sight that is ambrosia to the middle school teacher.

I get back to our cabin and I find V., one of the two students I’d promised they could get the campfire going.

“Are you guys getting the fire started?” I ask.

“We’re just going to play football for a little while, then start on the fire,” he replies. V’s been our main supervisor for Student Run Business this cycle and it shows. He’s been breaking out his calm, clear, confident, supervisor voice on the challenges all afternoon.

“We have half an hour until dinner and it will probably be dark afterward,” I say.

He just nods, seething competence.

It’s 5:45 and they’re still playing football. I look at my watch more and more frequently. I’m not going to remind them of what they have to do. We’re Montessori after all.

Two of the girls start working on the fire pit. Aha, I think to myself, this is going to get interesting. I saunter outside and my path nonchalantly takes me down to the fire pit. I suggest more kindling, they never get enough kindling. The boys realize other people are working on “their” fire.

Dissension in the ranks. Conflict. I tell them they should work together. Harsh words are spoken. A covenant broken. The poignant cry of impassioned idealism, “injustice”. Things fall apart; the center does not hold; Bethlehem is apparently somewhere on the other side of the playing field.

Ten minutes later it’s time to go to dinner, but first it’s time to rebuild, time to remind them of the covenant they came up with that very afternoon, time to have a short, quiet talk about the use of language.

Over dinner the laughter starts up again. I’m at the other table with Ms. A and her family, all of whom work at the camp in some degree or the other. After the last fifteen minutes I’m extra impressed by the calmness of her teenagers.

When we get back to the fire pit the laughter is perhaps a bit too loud, but the group seems back together again. The fire is started without recrimination (eventually because they did not have enough kindling).

We sit around the fire, reading stories, finding issues, being helpful writing partners, and learning how important it is to be critical, brutal even, to our own work. There are some really good writers in the group, and there’s nothing better than learning from your peers.

“Can we put our memoirs in the fire when we’re done?”

“Sure,” I say. Sharing our writing is supposed to be a celebration. Something strikes me as just about right about liberating these memories in flame, letting them take on a new, ethereal life. Burning pages in dancing flame, marking the putting away of cherished, childhood things; an adolescent rite of passage.

As the last few stragglers work on putting out the fire I sit there, on a cool fall night, thinking about cycles and the seasons. I wish I was on the beach, watching the tide come in, small waves advancing and retreating, bigger waves pushing them farther from time to time, every time a little closer to where they need to be.