Day 61: Onion Root Tip Lab


Science 9 – Today I thought I’d have the students try a microscope lab.  This is a pretty typical lab that is frequently done across all schools. Students are asked to examine a slide under a microscope and to see if they can recognize cells that are in the various stages of mitosis.  I think this lab would be extremely difficult with the above graphic to help.  At first, students will just see a few hundred cells that all look the same. It takes a reasonable amount of time before subtle differences are seen.  The above slide is more clear than what the students actually see because in order for the students to have this level of magnification the depth of field is much smaller.

One of the hardest things for the students to do is to actually get a slide in focus.  I had to spend a lot of time helping with this. My first suggestion was for them to initally focus on a piece of lettering that was on the prepared slide.  However, many students would only have their slide in partial focus. I found that very interesting – I don’t know why a person would stop focusing, or keep playing with the focus and see that the sample because sharper and sharper.

Day 60: Applying Fnet Model to Problems


Physics 11 – Today the students were given a handout to summarize all the types of forces they have learned up to now.  I then prompted the students to solve some word problems, and went over the solutions after everyone had tried them.  By “everyone” and “tried”, I really mean that.  I’m well aware the studenting that happens in high school.  Many students sit there, fake it, or take bathroom breaks, so that they can simply copy down the correct answer once I go over it.  The solution?

  • Walking around, the classroom, help the ones that are truly stuck
  • Mostly leave alone the ones that are getting (but still check in)
  • Finally reveal an answer once everyone has seriously tried the question

I even heard students say they were going to wait until I go over it.  I’m not sure what they would learn from that.  Surely me going over it is no different from reading a textbook, or close to it.

Day 59: Learning the Cell Cycle


Science 9 – The students are learning about the cell cycle and mitosis.  They were asked to complete an activity, but in general the students weren’t working too hard.  Homework is a foreign idea to most of them. I don’t assign homework for practice, but if I feel that something should have been finished in class, I will ask that it gets done at home.  I try to frame it as being an important part of their learning.  The work they do is for them, not for me. I have no interest in collecting it for marks.  However, I am interested in looking at it so I can the students feedback on what else they need to work on.

There is a lot of vocabulary around the cell cycle and mitosis, and as teachers I think we need to be careful on what we ultimately want them to take away from the topic. I expect the students to know the general idea of cell division, cell cycle, cell functions and mitosis.  They should also be able to identify pictures of mitosis: they’ve read about it, studied the pictures and will do a lab looking at onion root slides.  As well, with critical thinking, students should be able to figure out the correct order for the stages of mitosis, even if they didn’t memorize the pictures.

Day 58: Unbalanced Forces Results


Physics 11 – Today the students wrote up their results from their lab for Newton’s 2nd Law. Many groups were getting close to developing a model for Newton’s 2nd Law: Fnet = ma.  Since the input for the lab was a force though, the students graphed a = Fnet/m

Once the slope was written as a fraction, the students were able to recognize that it was the inverse of the mass.

I have two classes of physics 11.  During the first class, I walked along a lot and spoke with students as they worked.  As a result, by the time we got to share the whiteboards, almost everyone had the same board. For example, I challenged groups to find better symbols to use, rather than x and y.  The second class I helped a lot less and the following discussion was better.

After our discussion, the students applied their new model to the situation of someone standing on a scale inside an elevator.  This allowed for some thoughtful thinking on adding forces together from well drawn force diagrams.

Day 57: Immune System



Science 8 – Students began learning more about the immune system today.  I say “more” because the kids already know a lot. I started off with a powerpoint slide show of the main topics.  Most of the time though, we were doing class discussions.  The students told me about vaccinations, inflammations, 4 ways to contact pathogens, and a few other things.

I then asked the students to make a comic that addressed all of the issues we had discussed, including innate and acquired immune response, t-cells, antibodies, etc.  The idea with the comic is for the kids to learn some facts (knowledge, low level Blooms), apply your understandings and then make something new with it (synthesis).

The students did okay, but it was pretty common for kids to skip details. I gave each student individual verbal feedback on their comic after handing it in.  No marks were given, as I made it clear that they were learning exactly what they needed to know to do well on their immune system quiz.

Day 56: Unbalanced Forces Lab


Physics 11 – Today the classes did the main modeling lab for unbalanced forces and Newton’s Second Law.  I’ve used the modified atwood lab in the past, but wasn’t satisfied with it due to friction and hand-waving with transferring mass from cart to hanging mass.  I also tried to setup an atwood apparatus as described by Josh Gates.  In this setup, you hang a mass from one side of the pulley, and on the other side you hang another mass via a force sensor.  If you time how long it takes for the force sensor to travel a certain distance, you can calculate its acceleration.  You get the Fnet directly from the force sensor. I also found this lab setup to be difficult, particularly because it really works best with a wireless force sensor.  In the end I opted to have the students get data directly from a force and motion simulation.

Prior to starting the lab, we qualitatively discussed unbalanced forces via Peer Instruction.  I did this instead of the suggested modeling lab with qualitatively measurement of pulling a person on a cart.  PI afforded some good discussion and I’m relatively confident that students understood the idea of unbalanced forces causing an acceleration.