Today? The wonders of cell division! In lecture, I framed mitosis in the context of cancer: in order to understand unregulated cell growth, we need to understand how cells operate the rest of the time. As for meiosis, that’s the gateway to understanding reproduction. (Or maybe reproduction is the gateway to understanding meiosis? Either way, they’re intimately connected). This is a pretty important concept in biology, and while I don’t think they’ll need to be able to remember all the little details on into the future, I did want them to have a really clear understanding of what happens during cell division, so we attacked it in a variety of different ways.
First: A draw-along. I interrupted lecture, and asked them all to pull out a piece of paper. Then, using Skitch on my computer, I drew out the phases of mitosis, and had them draw along with me.
Second (Which turned out to be the highlight of the day): MICROSCOPY!!!!!!!!
Honestly, I think pulling out the microscopes is one of the easiest ways to catch everyone’s interest. THEY LOVE MICROSCOPES!!!!
We did the classic “onion root tip” experiment . . . looking at prepared slides of a part of the plant where growth – and therefore mitosis – is occurring. The idea is to count the individual cells, and which phase of mitosis they are in, and use that to get an idea of what percentage of time a cell spends in each phase. We didn’t start with microscopes, though. To give them some practice identifying the stages of mitosis, we worked through this virtual lab:
After that, we did pull out the compound microscopes, and they spent the next half hour or so counting onion cells. One thing I thought was clever: some of the groups took photos (through the microscope, like mine below), and counted the cells on the photo, instead of through the microscope. This turned out to be SO much easier to keep track of the rows.
When I complied all their data together, we found (as expected) that cells spend the most time (by far) in Interphase.
Third: to reinforce the phases of mitosis in yet another way, I had them do a hands-on activity where they physically manipulated a set of “chromosomes” through the process. The previous evening, I’d made up several sets of these “chromosomes” out of Perler beads and pipe cleaners. I’d hoped that the pipe cleaners would hold the beads in place, but also allow students to remove some of them easily, to swap strands when they simulated crossing over of meiosis I. I wasn’t sure how well they’d work, but they ended up working GREAT, and the students seemed to really enjoy the activity. I also provided them with printed “cell” templates, along with a bunch of colored markers that they could use to draw out the phases. First, they worked through mitosis, and then, after lunch (and the meiosis lecture), they did the same thing again with meiosis. I was super happy with the way this one worked out – I was a little afraid it would be boring, or that they’d get through it too quickly – but the pacing was just fine.
After finishing up with meiosis, I switched gears entirely, and gave an art lesson. Yes, you read that correctly – an art lesson: Drawing for Biology. It was grounded in the fact that the art of illustration – being able to accurately draw something you see – has always been an important part of biological research. I also fear that it’s one of several naturalists skills that aren’t as much a part of the biology curriculum anymore, as I think they should be. So, I decided to give an art lesson a try. I’m going to go into more details in a future post, but in a nutshell, after giving them some background, I asked them to do an exercise. To draw this flower. The catch? They weren’t allowed to look at their hands or the paper. The could ONLY look at the flower. Here’s one that I did . . .
Did the flowers look crappy? Well, yes – the petals aren’t in the proper relationship to one another. But if you look at the individual petals, most of them are actually pretty close to being the correct shape. The point, of course, was to help them switch from drawing what they think they’re seeing, to what they’re actually seeing. Next, I did let them draw the flower without the “no looking at the paper” restriction. (I also gave everyone a little “field notebook” – I’d purchased them in bulk from Amazon, and they worked out really well)
Finally, we went outdoors, to a little garden in the courtyard, and I asked them to choose anything and draw it. Again, I’m so impressed with this particular group of students – they all dove right in, and worked diligently on their drawings (I’d kind of expected at least some of them to rush through, since they were able to go home afterward, but they all stayed and put an appropriate amount of effort into the process).
Stay tuned for more of our drawing adventures later in the semester!