Monthly Archives: February 2019

Teaching in BIOL 121 (Genetics, Evolution and Ecology) – Population Genetics

CATL Teaching Practicum, Certificate in Advanced Teaching and Learning Program (CATL)

This was my second opportunity teaching in BIOL 121, although this time I was teaching course content rather than a guest lecture. I chose to take the introductory lesson on population genetics, as I enjoy the topic and also find that it can be challenging for first-year students. When I was in my first year, I remembered that I struggled a bit with the concepts. For this lesson, I took the time to sit and ponder what had made it difficult for me to understand – the material itself, or how it was taught? I suspect it was a mixture of both.

When Darwin and Wallace first compiled their thought on evolution by means of natural selection, it was not known what biological mechanism was allowing for selection to take place. It took a number of decades before it was discovered that there were certain elements within an organism that dictate certain traits, which we now call genes (it is important to realise that Darwin and Wallace completed their works in the mid-19th century, whereas the discovery of DNA and its establishment as the material of our genetic code only occurred nearly 100 years later in the mid-20th century). We now know that mutations in the genetic code are what generate the variation necessary for evolution to act upon. Thus, the prevailing logos: ‘Genes mutate, individuals are selected, populations evolve’. This was the message I wanted to clarify to the students, especially as they had just learned about mutation. I began with an example to clarify how changing environmental conditions led to a shift in frequencies of certain genes in a population of moths, as one type was selected for over time. I made sure to stress in this case how it was the population and not the individuals that was evolving. Because of the complexity of the topic, I chose to use the moth example throughout the lesson in order to keep a familiar aspect to new material as it was introduced.

I started the lesson with an iClicker question which was designed to assess the students’ understanding of some terminology. The idea was to see whether they would be comfortable with me using the terminology during the class. I think that this was useful and helped me avoid confusing the students with new terminology. I then introduced the Hardy-Weinberg model of genetic equilibrium which we would be working with in the class, which is one of the fundamental models of population genetics and evolutionary biology. This model essentially describes what we expect to see if evolution is not occurring at a specified location in the genome; in other words, it is a null model. This concept was a bit confusing but I was careful to work through it with a few examples, once again using the moth example to keep things simple. I then had the students try applying the model on their own using an iClicker question. At this point I was confident that they had a grasp of the concept and we moved on to a worksheet which the students worked on for the rest of the class.

I think this lesson went quite well, and there were only a few small issues. Namely, I may have still used too much jargon (this is the field that I do my research in, so it is easy to forget that students in first-year may have no background whatsoever). I also should have budgeted a few more minutes for a final question I wanted to ask at the end of the lesson, as students began packing up and leaving a few minutes before the end of class (this is always a problem, but it’s important to remember and try to work around it rather than fight it, mostly since students often leave early since it can take a long time for them to cross campus and arrive at another class). Now that I have taught a few full lessons, I am seeing the differences in designing lessons for 50 minute vs. 80 minute classes. The extra half-hour really impacts the lesson design and by extension the overall course design. It’s something that I will consider more when designing lessons in the future.

Observation of BIOL 121 (Genetics, Evolution and Ecology)

CATL Observations, Certificate in Advanced Teaching and Learning Program (CATL)

Last week I sat in on another lesson in BIOL 121, this time taught by Dr. Bridgette Clarkston. This lecture preceded the lesson I was going to teach in her class, and directly connected to it. The lesson included the introduction of the evolution unit of the course, which is always interesting. A few years ago, I was a teaching assistant for the course and the instructor at the time was very careful in introduction of the subject matter, as students (especially in first year) come into university with different belief systems and evolution can sometimes be a contentious topic. That instructor presented a concise summary of the history of evolutionary biology as a field and some examples of the volumes of evidence for evolutionary theory (including a discussion of the meaning of the term “theory” in science).

In this class, the instructor opted to skip over the more political aspects of the topic and went straight into sources of genetic variation, namely, mutation. I’m not sure which direction is really “best”. It might be better to skip all the debate and dive into the content, although you do run the risk of failing to include students with different belief systems, rather than trying to show them how their belief system can be compatible with the topic on hand.

The instructor used some contemporary examples from recent news to introduce the topic, which I thought was a nice touch. This makes the lesson feel new and fresh, and not as if it hasn’t been updated in a few years. It was also clear that the instructor was using weekly pre-class quizzes to make sure the students were completing the reading and coming prepared to class. Especially for this topic, and the topic that I taught in the following class, the concepts were new and a bit difficult, and I could tell that most of the students had completed the readings and were prepared for the activities.

The instructor used iClicker questions to run polls to gauge student understanding, which I thought was helpful and thus integrated into my own lesson plan. She also had students do some “think-pair-share” activities to follow up iClicker questions. Some of the iClicker questions involved a case study that the students had previously covered in the genetics module, now with new concepts introduced. I liked this approach, which is something that I try to do in my own lessons. It’s nice to have lots of exciting examples, but sometimes it’s best to explore a single example from multiple angles in order to decrease the complexity of a topic and demonstrate how most concepts in biology are interconnected as a system.

The final activity was one I had not seen before. The students were given “scratch cards” to work on in groups along with a sheet of multiple-choice questions. The purpose of this activity was to determine the extent of background knowledge in evolutionary theory students were coming into the course with. Students needed to read the questions, choose an answer, then scratch it off on the card. Behind the right answer was a star. If they got it right in the first guess, they would get four points. Otherwise, they would get a decreasing number of points for each successive guess. I worked with one group and overall it was a fun activity which also helped the instructor get a better understanding of where the students stood. The downside was that it was near the end of class and many students left without finishing or returning their scratch cards. I think I would improve this by giving it more time and following up with some iClicker questions to gauge student response to the activity.