Tag: classroom

The 10 minute in-class essay

When I was a student I hated writing tests and examinations with the intensity of a thousand flaming suns. Now that I get to set the curriculum, I actively look for alternative assignments to tests and exams that I can use in my classes. One assignment that I’ve had a lot of success with is the 10 minute in-class essay. It’s quick to administer, flexible, and doesn’t take a lot of time to mark.

At the beginning of the semester I tell my students that I will be offering 7 opportunities to write an in-class essay during the course and that they should make sure that they always bring a few sheets of paper and a pen with them to class. I ask that my students complete 5 of the in-class essays. Each essay is worth 2% and the total towards their final grade is therefore 10%. The dates of the in-class essays are not disclosed to the students, but at the beginning of the semester I work out which dates I’m going to be offering the essay opportunities and try to spread them out over the semester. This is where the flexibility comes in. Since I only require 5 essays to be completed, a student could miss 2 opportunities completely (due to illness or other life events) or could do poorly on a few and still earn a good mark on this assignment category. A student could complete all 7 and I will then calculate their mark based on the best 5 essays. The assignment also encourages students to come to class because they don’t know when I’ll offer an in-class essay and it forces students to keep up with the material because the essays are based on the content of that class or the class before. The students like the flexibility of the assignment and the fact that each one is low stakes, so it doesn’t cause a lot of stress. It also provides me a quick way to check in with my students to see if an important concept is not being taught or learned effectively.

Prior to a class in which I’m going to do an in-class essay I put together a slide that contains the question that I would like the students to answer. I try to make this question as open ended as possible and ideally it could have several correct answers depending on how the students are interacting with the course content. In class we do our normal activities and lecture and I use 15 minutes of our in-class time to run the assignment. It takes the students a few minutes to get their paper and pen out and to put away their notes and laptops. I put the question up on the screen and give them 10 minutes to write a few paragraphs in order to answer the question. I circulate around the room to address any issues and then collect the essays. Depending on my schedule I run the in-class essays at the beginning of class (this very effectively discourages tardiness), the middle of class, or at the end of class. In the next class period I take 5 minutes to explain several of the possible answers and to clarify concepts if I saw that common mistakes were being made.

So what does one of these questions look like? As an example, in my Endosymbiotic Theory course we do a section on the origin of mitochondria. The prevailing hypothesis is that mitochondria were once free living bacteria until they invaded or were ingested by another cell. We talk in class about the various lines of scientific evidence that support this particular hypothesis. My in-class essay for this section of the course is the following:

 Antibiotics in medicine that are used to treat infections in people are very effective in disrupting metabolism, cell walls, membranes, transcription and/or translation in bacteria. Given the hypothesis that mitochondria are derived from bacteria, explain why antibiotics are not toxic to humans.

An answer that would earn the full 2% might talk about how mitochondria possess an outer membrane derived from the host organism and an inner membrane derived from the bacterium. They might suggest that the antibiotics have no effect on the outer membrane or cannot penetrate it and therefore the mitochondria are impervious to the drug’s mode of action.

An answer that would earn 1% would talk vaguely about membranes, but wouldn’t clearly explain the rationale behind the answer.

An answer that would earn 0% would be one where the student puts seemingly random facts down on the page that don’t form a cohesive answer to the question.

There are alternative answers to this question that do not involve membranes (e.g. gene transfer to the nucleus, loss of drug targets over evolutionary time, etc.) and if the student is able to make a compelling and convincing argument to answer the question I am flexible in the answers that I accept.

I find the 10 minute in-class essay to be a great evaluation tool and an effective way of assessing what my students are taking away from my classroom. I am often impressed by the answers that my students provide which reveal their creativity and problem-solving abilities.

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Introducing a Blogging Assignment into a Graduate Course

This term I am teaching a graduate course on Ecological Physiology. When I was designing the course I wanted to provide the students with an opportunity to write about science for a more general audience. At the same time, I had recently started blogging and using Twitter and was starting to see the usefulness of these forms of communication and felt strongly that these are practical skills that should be taught to graduate students within the curriculum. I therefore thought that I’d like to add an assignment to my course that required my students to write a blog post.

The assignment requires my students to select a recent scientific paper (less than 5 months since publication) that they find interesting and that they believe would make an interesting blog post. We’ve had several meetings to discuss their papers and their approach to writing and publicizing their blog post. Their performance will be evaluated on the content of their post (e.g. writing style, writing effectiveness, etc.) and the popularity of their post as measured by page views.

This Friday I will feature two guest blog posts by my students on the research papers that they have selected. As this is the first time using this assignment I expect that I and the students will learn a great deal and I look forward to sharing the results of this experiment!

Active Learning Exercises for Teaching: Photosynthesis

I teach a 3rd year Plant Physiology course and a 4th year Environmental Stress Biology of Plants course. In both of these courses I go into quite a bit of detail about photosynthesis. This is material that my students have been exposed to in previous undergraduate courses, but in the context of these two courses my aim is to show students why the process of photosynthesis can be a double edged sword. I think that most people assume that plants love any level of light and that the more light that plants have access to the better. We often talk about photosynthesis as a steady-state pathway when in reality plants are constantly acclimating to their light environment likely on the timescale of milliseconds. I use an active learning exercise in my classroom in order to teach my students that photosynthesis is a dynamic process fraught with dangers for plants.
For this exercise I bring in a bag of soft plastic balls. These were left over from a ball play-set that my son had when he was younger (think the ball pits that you can find at IKEA or that used to be present at indoor play areas). I also bring in a large metal bucket. I ask for 6 volunteers from the audience to participate in the activity. Each student represents a complex/mobile carrier involved in the photosynthetic electron transport chain (e.g. photosystem II, plastoquinol, etc.) and the last student in the row is the enzyme ferredoxin-NADP+-reductase. The balls are used to represent electrons. The first student’s job is to accept the balls that I pass to them and then pass them to the next student. The other students in the chain in turn accept the balls and pass them along the chain. The last student in the chain aims to deposit the balls in the metal bucket. The bucket represents the ability of the plant to use the electrons to produce NADPH and ATP and to fix carbon.
The first time through the exercise I put balls into the chain at a very low rate. This shows the students that sometimes plants can have difficulty generating energy and fixing carbon if light is limiting. This would be similar to severe shading effects for example. I then put the balls into the chain at a reasonable rate. This represents a “steady-state” for photosynthesis where the process is running efficiently. For the last part of the activity I put the balls into the chain at an extremely high rate; as quickly as I can pass the balls to the first student in the chain. Inevitably the balls get dropped frequently at various parts of the chain and many of the balls do not make it into the bucket, or the bucket overflows. I use this to demonstrate over-reduction of the electron transport chain and to explain the generation of reactive oxygen species during photosynthesis.
Based on previous course evaluations, the students enjoy this exercise and claim that it helps them to remember key aspects of the photosynthetic electron transport chain. I’ve found it to be an engaging and effect way to teach about photosynthesis in my classroom.