“Practice Perfection”: It’s Not Just for Gymnasts

In case you are not focused on the world of college gymnastics, the University of Oklahoma’s men’s and women’s teams are second to none. I am not exaggerating: You can see the 2019 NCAA men’s rankings here and the women’s rankings here. We really are #1. Hey, it ain’t bragging if it’s true.

This isn’t a sports blog though; it’s a blog about teaching nonmajors biology. Where’s the connection? Well, I’ll get to that. But first, some back story.

Four of OU’s gymnasts recently spoke at an OU Honors College Q&A session for students. Among the questions was, “How do you do it?”  That is, when competing in a meet, how do these athletes put aside the distractions and the pressure, focus inward, and put together a perfect routine? The answer was shockingly simple: “We practice perfection.” That is, they do the routine so many times that they can execute it flawlessly during practice. Then, they said, the competition is easy. All they need to do is complete the same routine in the meet that they have done over and over in practice.

These four OU gymnasts talked about “practicing perfection” at a recent OU Honors College event. [Photo courtesy of Lisa J. Tucker]

The connection to teaching biology is that simple piece of advice: practice perfection. If students studied course material until they knew it perfectly, every time, then tests would be easy. (Teachers aren’t exempt, of course. If we practiced our presentations until we could do them flawlessly, our classes would probably go more smoothly too! But let’s focus on our students.)

How many of your students hold themselves to the “practice perfection” standard? Some do, but many don’t. Instead, many students study just enough to get the gist of the material, then simply hope the exam is easy. If that hope is dashed, it’s easy to blame the teacher for writing “tricky questions” or to blame an innate flaw, like “I’m terrible at science” or “I have really bad test anxiety.” Can you imagine an elite athlete using that strategy? The athlete would practice enough to gain a passing familiarity with the routine, perform during the competition, and blame the judge (or an inability to compete) if the score is low. Such a gymnast wouldn’t last very long.

So, how can teachers help our students to see the value in practicing perfection? If a student professes to be “terrible at science,” we can help by encouraging a growth mindset. If the student has test anxiety, point out resources that can help — and if you click on the link to those resources, notice how many of them connect good study skills (i.e., practice) with confidence, relaxation, and the ability to perform well on tests. If the student grumbles about tricky questions, ask for specific examples, then have an open mind. Your questions really might be ambiguous or unfair. But if a supposedly tricky question is actually difficult but fair, turn the problem back on the student: “Where can you find the material needed to answer that question, and how might you study next time to be able to answer a question like that?”

One additional concrete step we can take is to give students plenty of help finding ways to practice. Give them old exams and answer keys — not all of them, but a couple. Show them how to use the end-of-section and end-of-chapter questions published in textbooks. (If you want to see the practice materials that I provide for my own students, head for my teaching website.) Use class time and office hours to reinforce concept mapping and other skills that help students get away from rote memorization and work toward a deeper understanding of the material.  Let’s do what we can to help our students do what the gymnasts do: practice perfection.

The Laptop Ban: New Research

Students taking photos in class instead of taking notes. Source: Flickr

Faithful readers may remember that a couple of years ago I banned the use of laptops in my nonmajors biology classroom. You can read about the rationale in a previous blog post that summarizes the Mueller and Oppenheimer study, which found that students performed best on conceptual questions when they took notes by hand. And you can see how I implement the ban and sell the idea to my class during week 1.

In course evaluations, surprisingly few students complain about the ban, perhaps because my class proceeds at a pace for which it is possible for most students to take notes by hand. One student last fall did gripe about it; his main argument was that he’s a grownup, he’s paying for class, and he should be able to use his class time however he sees fit. I am sympathetic to that argument, as students need to learn to manage their own time and resources at some point. However, that point of view focuses only on the would-be laptop user and not on the neighboring students who would be constantly distracted by whatever is happening on someone else’s glowing screen. Moreover, the desire to look at screens of all sizes seem to be contagious. That is, it’s easy enough to ignore your phone if no one is using one (e.g., during an exam), but it’s a lot harder when others around you are enjoying the dopamine rush that accompanies incoming notifications and social media posts.

Why am I bringing this up again? It’s because the Chronicle of Higher Education just did. They recently noted that researchers tried to repeat the Mueller and Oppenheimer study that you can read about in my previous blog posts. In the Chronicle’s words, “The new paper … couldn’t completely replicate those findings.” The Chronicle also points out what’s wrong with both studies, namely that taking a test 30 minutes after taking notes (as they did in both studies) is a whole lot different from taking a test 4 weeks after taking notes (as often happens in the college classes). It also makes sense that student study habits during the exam-free interval might be more important than how they took notes in the first place.

The article began by mentioning the problem of distracting the neighbors, but only briefly returned to that point at the end. For me, that will remain one of the primary reasons to carry on with the ban. Most students aren’t complaining, so I’ll stay the course.

Moldy bread, experimental design, and you

For many semesters, my nonmajors biology lab did a lab called chicken wing microbiology. You can download it here, from the wonderful Association for Biology Laboratory Education website (Walvoord and Hoefnagels, 2006). In the lab, students devised a method to kill the bacteria on chicken wings, carried out an experiment (including serial dilutions) to test their proposed method, collected plate count data the following week, and wrote a short lab report on their results.

One semester, a vegetarian student notified me that he would refuse to work with chicken, so we agreed that he could try the same lab with potatoes in place of chicken wings. It worked, and what was once a lab that consumed dozens upon dozens of chicken wings, plus nearly 1000 test tubes and petri dishes, became a lab that consumed a lot of small potatoes — but still used the same number of test tubes and petri dishes. It was still very resource- and labor-intensive to set up. Plus, if you have ever tried incubating 1000 petri dishes containing wild bacteria for a week, you know they stink.

So last summer, I was looking around for a substitute that would be cheaper and easier to set up and that would use less space to complete than 1000 petri dishes. I happened upon a lab in Biology Brought to Life by Handelsman, Houser, and Kriegel. If you are not familiar with that book, it’s a unique product that focuses on active learning. The book has a lab called “Bread, mold, and environment: a lesson in biology and the environment.” Its focus is the Host – Pathogen – Environment disease triangle, with bread standing in for the host and bread mold standing in for the pathogen (while acknowledging that bread isn’t alive and that bread mold doesn’t cause disease). The lab challenges students to “develop a hypothesis about the environmental factors that might affect the ability of Penicillium to grow on bread and design an experiment to test your hypothesis.”

That turned out to be the inspiration I needed for our new lab. Sarah (my capable undergraduate assistant) and I unleashed the Summer of Mold to figure out whether we could have students test predictions about mold growth by spraying spore suspensions or sterile water control solutions on various baked goods. The first step was to figure out what type of baked goods would work the best. Sarah scoured the stores and came back to the lab with a huge variety of treats, including cookies, Twinkies, muffins, sweet breads, sandwich breads, garlic breads, and more. We sprayed, and then we waited. As you can see in the photos below, some baked goods got moldy. A lot of them did not.

Mini-blueberry muffins and cinnamon swirl bread. No mold! Photo by M. Hoefnagels.

Garlic bread slices and Twinkies. The Twinkies are pristine (and remain so to this day). Photo by M. hoefnagels.

One major finding was that the easiest baked goods to interpret were plain slices of sandwich bread, and further pilot testing revealed that quarter slices of bread would work just fine.

Fresh bread from a bakery got moldy, even after being sprayed with sterile water. Photo by M. Hoefnagels.

So for week 1 of the final lab, we decided to have students pretend they were opening a bakery but unable to decide whether or not their bakery’s bread should contain artificial preservatives. We let them think about how they might test the effect of preservatives on mold growth if they were given a squirt bottle containing mold spores and bread slices of two types: store-bought whole wheat bread with artificial preservatives, and fresh, bakery-bought bread without artificial preservatives. Once a TA approved their methods, they went at it. We had plenty of space in the back of the classroom to incubate all of the ziploc baggies at room temperature.

During week 2, each group had to figure out how to quantify the mold growth on their bread slices. We gave them plastic transparencies marked with 1-cm2 grids and asked them to figure out how to use the grids to generate their data (without opening their baggies). Once a TA approved their proposed methods, they collected their data, produced their graphs, and wrote their reports.

Good news: It worked! Freshly baked bread without preservatives typically got very moldy indeed, whereas store-bought bread with preservatives hardly had any mold spores at all. Below is an example of a graph submitted with a student’s report.

Sample graph; used with permission. In the color key, “Mold” refers to the mold spore suspension; “Water” refers to sterile water. No mold grew on store-bought bread sprayed with sterile water.

If you’re thinking of doing a lab like this, it does take some planning. A couple of weeks before the lab, you’ll need to sterilize several liters of water (and quite a few squirt bottles). You’ll also need to buy a Penicillium culture and some extra plates of potato dextrose agar, inoculate the plates with your Penicillium, and let the plates grow for a week or two — long enough to generate the spores you’ll wash into the squirt bottles as you prepare for the lab. You’ll also need to teach students about aseptic technique and make sure they know to spray INSIDE the plastic bags, not outside — this is an important precaution that maximizes safety and minimizes cross-contamination.

Once it’s time for week 1, the materials needed are simple: bread, Lysol, plastic knives (for cutting bread into four pieces), cutting boards, squirt bottles containing sterile water, squirt bottles containing Penicillium spores, ziploc baggies (for incubating the slices for a week), and Sharpies. During week 2, you’ll need transparencies pre-printed with a 1-cm2 grid and water-soluble marking pens. For safety’s sake, you’ll also need to remind students never to open ziploc baggies containing moldy bread.

What did the students think? They liked it! It was not overly complicated, but it was reasonably challenging. The TAs told me that students would have liked more freedom to test different types of natural preservatives, but I confess that I am not sure how to do that without introducing confounding variables. However, it would not be difficult to add refrigeration as a treatment to substitute for (or add to) store-bought bread with artificial preservatives. In our July pilot studies, refrigeration substantially inhibited mold growth.

Anyway, it’s an open-source lab so if you want a copy of the lab and prep notes, leave a comment below and I’ll send them to you.

Raise Your Hand: How Do You Start the Semester on the Right Foot?

Years ago, I published my best idea for semester prep, a checklist that has proved to be an audience favorite. Over the past 5 years, many readers have asked for my checklist, which I have freely shared.

I was knee-deep in my checklist a few weeks ago as I was prepping for this fall semester. While I was checking off tasks, a colleague shared a really useful article about starting the semester with a culture of student participation: Structure Matters: Twenty-One Teaching Strategies to Promote Student Engagement and Cultivate Classroom Equity, by Kimberly D. Tanner. I like articles with the word “Strategies” in the title because that means I won’t have to plow through a lot of edu-speak to get to the practical suggestions. Tanner’s article doesn’t disappoint, and I wanted to share with you a couple of the ideas that I tried in the first two weeks.

A student raises his hand in class. Image Credit: UC Davis College of Engineering Photostream.

Under the category “Giving students opportunities to think and talk about biology” is a tip titled “Wait Time.” Tanner suggests that when you pose a question to the class, count to yourself “one thousand one … one thousand two … one thousand three … one thousand four … one thousand five” before acknowledging any answers. Remarkably, according to Tanner, instructors wait an average of only 1.5 seconds before filling the empty air with a student response or with their own. The extra time gives students who are not lightning-quick a chance to think about the question.

A related tip, in the category called “Encouraging, demanding, and actively managing the participation of all students,” is “Hand raising.” According to Tanner, “Novice instructors, sometimes awash in silence and desperate for any student participation, can allow the classroom to become an open forum.” That might not sound like a bad thing, but it could also exclude students who aren’t brave enough to shout out their answers. Combining wait time with hand-raising has two benefits: It gives students time to think and it gives the instructor a chance to choose who will speak. Both outcomes reduce the chance that the class will be dominated by a few outspoken students.

Speaking of hand-raising, Tanner suggests that instructors ask for at least three volunteers to raise their hands before acknowledging anyone. In her words, this strategy “allows instructors to selectively call on those students who may generally participate less frequently or who may have never previously shared aloud in class.”

Out of the 21 strategies, I’ll just choose one more to share: “Random calling using popsicle sticks/index cards.” For smaller classes, Tanner suggests filling a cup with popsicle sticks, each with a student’s name on it. When you want to call on a student, you simply pick one randomly out of the cup. For larger classes, shuffle those index cards you collect from students on the first day of class, and pick one.

So, how have I done with these strategies in my first two weeks? I guess I’d give myself a C. In some cases, I have encouraged students to raise their hands instead of calling out answers, and that has given me a chance to say, “Let’s hear from someone we haven’t heard from yet” or “Let’s see if someone on this side of the room wants to contribute.” I also tried the index card strategy during a lesson on experimental design. I pulled a card and called out the student’s name, only to find she was absent. I muttered “Well, this is going well,” the students tittered, and I tried again. That student answered the question I had offered — and probably would never have done so if I hadn’t gently forced his hand by calling on him. That was a win.

In other cases, though, I’ve succumbed to the satisfaction of listening to a whole class shout out the answer to a question they couldn’t answer the day before. However, Tanner’s article has made me realize something: When I say the “whole class,” I might not be including everyone; most likely, a few students remain silent. Breaking old teaching habits is hard, and sometimes I forget the tricks I told myself I’d try, but I will work to get better.

If your student engagement could use a boost, scan through the article and see which strategies speak to you. (In particular, check out “Do not judge responses” and “Use praise with caution,” both of which I also found especially enlightening.) I think you’ll be pleased with the scope and practicality of Tanner’s suggestions. If you end up trying some, please feel free to share your experience as a comment to this post.

Another Way to Connect Selection, Phenotype, and Genotype

Now that it’s summer, I’m catching up on my American Biology Teacher backlog. I found this interesting-looking activity by Janina Jördens and three coauthors in the February 2018 issue. The title of the article says it all: “Interrelating Concepts from Genetics and Evolution: Why Are Cod Shrinking?” I haven’t tried it — it is summer, after all — but it looks like it addresses some of the learning objectives that I have previously outlined in the oft-requested reptilobird and antibiotic resistance activities.

The authors point out that traditional activities illustrating natural selection — like picking scattered colored dots off a piece of patterned fabric — emphasize phenotypes while ignoring genotypes. But if evolution means changes in allele frequencies over multiple generations, we should not let students focus purely on changes in phenotypic frequencies. Jördens and her coauthors developed a simulation that could help students understand the connection between phenotype and genotype in the context of cod overfishing.

All of the materials needed for the simulation are described at the evolution-of-life website. As I discovered in writing this blog post, the site is not easy to navigate. Thank goodness for the site map, which led me to all of the site’s teaching materials, which led me to the teaching resources for this activity. Here they are. They include handouts with background information and instructions, the playing board, and teaching advice.

The lesson begins with an 8-minute video explaining how the average body size of cod has declined over time, thanks to decades of selectively harvesting the biggest fish. Students also read about the situation on handouts. Each group of five students then receives a playing board depicting 10 cod fish. They also get a non-transparent bag containing 60 colored plastic disks: 15 red, 15 yellow, 15 black, and 15 blue (or, less durably but more deliciously, chocolate candies with different colored wrappers). Separately, they also receive enough “spare” disks to make up a total of 60 of each color.

Each of the 10 fish on the playing board has room for six alleles, two for each of three genes (labeled as A1, A2, B1, B2, C1, and C2) that control the individual’s body size. The students begin by randomly drawing 6 disks from the bag (no peeking!) and placing them on the first fish on the playing board. They repeat that process for each of the remaining nine fish — if they have done it right, they should have used up all of the disks in the bag.

The upper third of the game board, showing where to put two alleles for each of the three genes (A, B, and C) conferring fish size. Screenshot taken from game board at http://www.evolution-of-life.com/fileadmin/enseigner/05_human_made_evolution/en/MATERIAL_board.pdf.

The colors represent different numbers of “size units,” with red conferring the largest size (4 units), followed by yellow (3 units), black (2 units), and blue (1 unit). With this information, students can calculate the size of each fish and compute the average size for the entire population of 10 fish. At this point, the largest five individuals are “caught” and their alleles are removed from the board before they have a chance to “reproduce.” The alleles from the surviving individuals are duplicated (to simulate reproduction) and the surviving alleles plus the duplicates are returned to the bag. At this point, the number of alleles in the bag should be back to 60.

Students are now ready to produce the second generation. They randomly assign each fish on the playing board its 6 alleles, measure the size of each fish, compute the average population size, and tally the frequency of each allele. Then the five largest individuals are caught, and the entire process is repeated to produce and measure generations 3 and 4. Afterward, students graph the individual and/or average body sizes for each generation; given the strong selection pressure against large body size, the trend should point downward. Likewise, the frequency of the red and yellow alleles should decline. The authors suggest several thought questions and followup activities that could be useful, depending on the instructor’s priorities.

For my part, I am happy to see more ways to connect selection, phenotypes, and genotypes. This simulation appears to be well-thought out, and the materials are freely available on the evolution-of-life website. By the way, I encourage you to explore the entire site. The “Teach” page has links to materials for the shrinking cod activity described here, as well as the origin of life, Darwin, evolution in fast motion, and coevolution. If I find other gems, I will certainly let you know; if you do, please leave a comment and let me know!

Reference:

Jördens, Janina, Roman Asshoff, Harald Kullmann, and Marcus Hammann. 2018. The American Biology Teacher 80(2):132-138.
https://doi.org/10.1525/abt.2018.80.2.132

So many learning resources … so little time

Contributed by Matt Taylor

Suppose you are searching for that great new activity, assignment, or video for your class. Do you ever feel overwhelmed by the never-ending list of resources that you can find? Your students might feel the same way about the abundance of learning resources available to them. The good news is that we can help students take control in the chaos.

Many teachers and educational developers want students to have a variety of resources to help them master concepts. Since student learning styles or preferences vary, it is useful to provide different tools for a diverse body of learners.

But more is not necessarily better if students don’t know how to use the resources available to them. To overcome this gap in understanding, teachers could tell their students how each learning resource might be useful. Or better yet, teachers could encourage students to develop their own strategies. It turns out that the latter—asking students to make deliberate study plans—has a small but significant impact on class performance, according to Patricia Chen and her coauthors in a 2017 Psychological Science article. The research team set up an experimental group of students who developed specific strategies to use learning resources and compared the performance and psychology of those students to others who made no deliberate study plans.

Students who made deliberate study plans improved their course grade by about 4%.

Chen and the other researchers conducted their experiment in two introductory statistics classes. All students in these classes received weekly reminders of what resources were available to them. Also, in return for extra credit points, students were given the option to take surveys before and after two midterm exams. Participation in all four surveys was around 60%. Upon starting the first survey, students were randomly assigned to the control group or the experimental group (the class instructor was blind to this assignment). Post hoc analysis of these groups revealed that their members were not significantly different in terms of past performance, motivation, or confidence.

Pre-survey: Students in both the experimental and control group were asked questions targeting four areas: what grade they wanted to receive on the exam, how motivated they were to receive that grade, how important it was to receive that grade, and how confident they were in success.

Then, only the students in the experimental group went on to answer questions about their study plans. The first question asked them to select which resources from a list would be likely to help them study for the exam. For example, in an introductory biology course using a McGraw-Hill book, the list might look like this:

• Textbook readings
• Connect questions
• LearnSmart questions
• Smartbook learning resources
• Tutorial animations
• Office hours
• Lecture notes
• Previous exams
• Lab materials

After making their selections, students described in essay format how each chosen learning resource would help them. Then, they were asked to describe in detail when, where, and how they would use each resource to study in the week before the exam (e.g., “on Monday morning I will go to the library to rewrite my lecture notes”).

Post-survey: All students received the same post-survey. It asked questions about what resources students had used and how useful they thought each resource was to their learning. They were also asked about how much control they thought they had over their own grades, how much they plan for an exam, and how well they follow through with their plans.

Results: Students in the experimental group who participated in at least one pre-survey scored approximately 4% higher than their classmates who did not make deliberate study plans. Students who made study plans before both tests got an even higher boost in overall course performance. (Importantly, the treatment effect remains statistically significant even when the researchers removed the extra credit points that students received for participating in the surveys.)

Finally, the researchers also found that students who participated in strategic study planning on a previous exam felt more confident, less anxious, and more in control of their grades on an upcoming exam.

The research article has many other details that I did not explain here, and I encourage you to read it for yourself. But the major takeaway is this:

If you encourage strategic planning of learning resource use, then your students will be more confident and successful.

Do you encourage students to plan and self-reflect on their learning? How does it work in your classroom?

Reference:

Patricia Chen, Omar Chavez, Desmond C. Ong, and Brenda Gunderson. 2017. Strategic Resource Use for Learning: A Self-Administered Intervention That Guides Self-Reflection on Effective Resource Use Enhances Academic Performance. Psychological Science, Vol 28, Issue 6, pp. 774 – 785. https://doi.org/10.1177/0956797617696456

Antibiotic resistance in the lab … with actual bacteria!

Apparently my post on the antibiotic resistance activity using green, yellow, and red beads was a big hit with instructors, because lots of people want a copy of the worksheet. I have been happy to oblige, and now I want to follow up by calling your attention to a potential companion activity in the March 2018 edition of The American Biology Teacher.

I hasten to add the disclaimer that I have not tried this lab in my own class; I only just read about it this week. But the title certainly seems promising: Modeling the Emergence of Antibiotic Resistance in Bacterial Populations.

The authors outline a 5-day procedure in which students expose a bacterial population to antibiotics at two different times. On day 1, students select a single colony of bacteria from an agar plate and suspend the cells in a nutrient broth. The bacteria-laden broth is then swabbed across the surface of an agar plate. Students then place paper disks with and without antibiotics on the plate. The bacteria on the plate are allowed to grow overnight in an incubator and are then placed in the refrigerator until day 5. Meanwhile, the original broth also incubates overnight. On day 2, the instructor transfers bacteria from the broth into fresh broth and again allows the cells to multiply overnight in the incubator. On day 3, each student group swabs the resulting inoculum onto a fresh agar plate and adds disks with and without antibiotics. Like the plate from day 1, this plate is allowed to incubate overnight and is subsequently stored in the fridge until day 5.

On day 5, it’s time to collect the data. Students examine their plates, measuring the zone of inhibition around each antibiotic-infused paper disk. They use the data they collect to test two models of antibiotic resistance. According to the article, “Model 1 illustrates need-based acquisition of antibiotic resistance. Here, the bacteria rapidly gain antibiotic resistance only when exposed to the antibiotic.” If model 1 is correct, then the number of resistant colonies arising from the “day 1” swab should be equal to the number of resistant colonies arising from the “day 3” swab. In contrast, “Model 2 illustrates acquisition of antibiotic resistance through mutation. Here, the bacteria acquire mutations over time that increase their level of resistance to the antibiotic independent of antibiotic exposure.” If model 2 is correct, then the bacteria plated on day 3 should have more mutations — and more resistance — than those plated on day 1.

The article contains great illustrations, explores the molecular mechanisms of antibiotic resistance, introduces the idea of intermediate resistance, and has lots more information about how to implement this activity. The authors also offer student handouts and even a PowerPoint presentation. I can’t endorse it because I haven’t tried it, but heck, if you’re looking for antibiotic resistance activities that actually involve growing bacteria, you might want to check it out.

Reference:

Michelle A. Williams, Patricia J. Friedrichsen, Troy D. Sadler, Pamela J. B. Brown. Modeling the Emergence of Antibiotic Resistance in Bacterial Populations. The American Biology Teacher, Vol. 80 No. 3, March 2018; (pp. 214-220) DOI: 10.1525/abt.2018.80.3.214

Attend the best conference for people who teach biology labs … for free!

This is a good time to direct your attention to my favorite professional organization: The Association for Biology Laboratory Education, or ABLE.

I raved about ABLE in a previous post, and I won’t repeat my praise here. I just wanted to let you know that the 2018 conference will be at The Ohio State University from June 19-22. Registration isn’t open yet, so I can’t tell you the cost … but it’s typically in the $300 range and includes quite a few meals.

Are you thinking to yourself, “I can’t afford that!”? If so, I have good news for you. ABLE grants a limited number of registration waivers for graduate students, post-doctoral fellows, new academic faculty/staff, and faculty/staff from community colleges. You don’t even need to be an ABLE member to apply. (If you feel inspired to join, it is a real bargain at $15 for students/post-docs and $35 for everyone else.)

Now you are probably thinking to yourself, “That sounds great!” If you are, then hightail it over to the registration waivers website and apply by March 5. The application is simple. It collects basic information, asks you to describe “how attendance at this conference would be of benefit to you personally and/or your institution as a whole,” and then requires you to upload a CV and a letter of support from your chair. It’s that easy!

If you are awarded a grant, you can enjoy a meeting full of hands-on activities and wonderful, collegial colleagues on ABLE’s dime. (Note that travel and lodging expenses are not included.) I urge you to give it a try; you won’t regret it.

Antibiotic-Resistant Bacteria: A Simple, Realistic Lab Activity

Every now and then I write a blog post about lab activities that worked in my nonmajors biology class. For example, I have written about reptilobirds (an activity combining meiosis and inheritance), staining banana cells to illustrate digestion in plants, and building models of protein synthesis with candy.

Here’s another topic that nonmajors (and everyone else) ought to know about: the development of antibiotic resistance in bacteria. If you teach biology, you might have learned about antibiotic resistance so long ago that you assume everyone else knows about it too. However, I learned this semester that the misuse of antibiotics is still a real problem. During the week before our “Bacteria and Disease” lab, one of my students came into my office with clogged sinuses. He looked miserable and said that he’d been sick for weeks. He then reported that he had taken some of his roommate’s leftover antibiotics, and although he felt better for a while, he soon got worse again. You did what?! Of course you got sick again! How could you not know that was a bad idea?! I scolded him (more gently than that) and mentally reminded myself that education really does matter.

Staphylococcus aureus. Source: Wikimedia commons

Of course, our lab manual already has an activity that addresses antibiotic resistance. I tried it once or twice. Students used different types of colored pencils (representing various strains of bacteria) to fill in a diagram of lungs in the lab manual. When they tried to erase the pencil marks (i.e., used antibiotics to kill the bacteria), they discovered that not all of the marks would disappear. They were supposed to conclude that antibiotics don’t kill all types of bacteria. The activity was so dull, predictable, and ineffective that I soon abandoned it. For many semesters we’ve showed a video about antibiotic-resistant tuberculosis bacteria instead.

But then I read this article by Eva M. Ogens and Richard Langheim in The American Biology Teacher and I decided to give one of the activities a try. It was appealing because it connects antibiotic resistance directly with something that nearly all students have done: taken a prescription of antibiotics. The simulation uses dice and inexpensive pony beads to model the evolution of bacteria over a course of antibiotics. The pony beads are in three colors to simulate three degrees of resistance to the drugs (we used green for least resistant, yellow for resistant, and red for most resistant).

After a brief introduction, each pair of students is given a petri dish containing a “bank” of 20 green, 15 yellow, and 15 red pony beads. Each student transfers 13 green beads, 6 yellow beads, and 1 red bead to a separate dish, which represents the body and the bacteria currently infecting it. Students are told they are taking antibiotics to fight the infection. They are then instructed to roll the die and record the number in a table. Rolling a 1, 3, 5, or 6 means they remembered to take the antibiotics and get to remove 5 bacteria from the body. Least resistant bacteria die most easily, so green ones are removed first. Once there are no more green ones, yellow ones can be removed. Red ones die last. Rolling a 2 or 4 means they forgot to take their drugs.

The die, “body” (dish with four surviving red beads), bead bank (dish with many beads), and data sheet. Photo by M. Hoefnagels.

Critically, the next step is reproduction: Students add one more of each color bead that has survived in the “body.” This was the only stage at which students tended to make mistakes. Some pairs forgot to do the reproduction part entirely; others put green beads back in the body even after all the least resistant bacteria were supposed to be dead. Both errors change the outcome of the activity, so clear instructions are essential.

Students then repeat the roll/removal/reproduction steps. At each round, they record the number of bacteria remaining until no bacteria remain in the dish. Afterwards, they answer questions on the worksheet. Most of the questions are fairly straightforward, but we were surprised at how many students had a hard time articulating the relationship between bead colors (representing genetic diversity) and the events of natural selection (less “fit” bacteria were eliminated first, leaving the best-adapted to pass their resistance alleles to the next generation).

One of the strengths of this activity is that the bacteria fall into a spectrum of resistance. I’ve observed that even thoughtful students have trouble understanding why antibiotic-resistant bacteria would ever die in the presence of antibiotics. The somewhat-resistant yellow beads and the more-resistant red beads remind students that most bacteria are vulnerable to antibiotics, but some are more resistant than others. Natural selection acts on this genetic diversity.

Note that this simulation lends itself well to graphing activities. One simple idea would be to have students graph the number of bacteria of each color over time. Another would be to collect the data from the entire class and have students graph the relationship between the number of times the antibiotics were forgotten and the number of rounds of antibiotics required to kill all the bacteria.

The writeup in The American Biology Teacher is very good, with one exception: It is difficult to discern from the narrative that 5 bacteria should be removed at each round. We developed a handout that clarifies the instructions and includes a detailed table for recording data. If you want a copy, please leave a note in the comments section and I’ll email it to you.

Reference:

Spreading Disease – It’s Contagious! Using a Model & Simulations to Understand How Antibiotics Work. Eva M. Ogens, Richard Langheim. The American Biology Teacher, Vol. 78 No. 7, September 2016; (pp. 568-574) DOI: 10.1525/abt.2016.78.7.568

Selling the laptop ban: An activity

In my last blog post, I reported introducing a new no-laptop policy in my nonmajors biology class. We just finished week 3, and things are going well — there has been no pushback, and I really enjoy looking out at a sea of faces instead of the lids of their laptop computers.

Image source: Wikimedia

One of the studies that influenced my to-ban-or-not-to-ban deliberations over the summer was a study describing three experiments by Mueller and Oppenheimer. In a previous blog post, I went over the study in some detail; I’ll pull out a quote here from that post:

In the first experiment, students watched TED talks and took notes either longhand or on laptops that were disconnected from the Internet. Half an hour later, the students answered factual recall and conceptual application questions about the talks. Although the two groups did not differ on the factual recall questions, students who took longhand notes did better on the conceptual application questions. The researchers also found that students who used laptops wrote more words than those who took longhand notes, and that the laptop users had much more “verbatim overlap” with the lecture content. What the authors called “mindless transcription” predicted lower performance on the post-lecture questions.

To help my students understand why I adopted this policy, I used my “process of science” class during week 1 to explore this first experiment. After introducing the elements of an experiment, I distributed the abstract for the Mueller and Oppenheimer article:

Taking notes on laptops rather than in longhand is increasingly common. Many researchers have suggested that laptop note taking is less effective than longhand note taking for learning. Prior studies have primarily focused on students’ capacity for multitasking and distraction when using laptops. The present research suggests that even when laptops are used solely to take notes, they may still be impairing learning because their use results in shallower processing. In three studies, we found that students who took notes on laptops performed worse on conceptual questions than students who took notes longhand. We show that whereas taking more notes can be beneficial, laptop note takers’ tendency to transcribe lectures verbatim rather than processing information and reframing it in their own words is detrimental to learning.

I asked the students to work in groups to write a testable hypothesis in IF … AND [test] … THEN [prediction] format, using information from the abstract. This turned out to be a challenge; about half of the groups resisted proposing an “IF” explanation. That is, I was hoping for something like this: “IF taking notes on a laptop promotes shallower processing, …” A typical response, however, was “IF taking notes longhand rather than with a laptop is better, …”

After some discussion, however, we settled on a suitable hypothesis. I then gave them 10 minutes to propose an experimental design to test the hypothesis, including independent variable, dependent variable(s), and standardized variables. This went more quickly than expected, and when they shared their designs it was clear that most groups did not find it difficult.

Next, I revealed the design of the first experiment in the Mueller and Oppenheimer study. In a nutshell, 67 students watched a TED talk and were told to take notes either with a laptop or with pen and paper. Afterwards, all subjects did 30 minutes of memory tasks unrelated to the TED talk. Everyone then took a test containing factual and conceptual questions about the TED talk.  Using this information, I asked each group to draw a graph of the predicted results on the board. Most groups had no difficulty deciding on a bar graph or determining which variable should go on which axis. Interestingly, however, only one or two groups differentiated between the two dependent variables (performance on factual questions and performance on conceptual questions); most just used “test score” on the Y axis.

I then showed figure 1 from the paper, so students could compare their graphs to the corresponding graph from the actual study. Students seemed pleased to see that their graph-drawing instincts were correct.

Well, we were about out of time! I briefly showed the remaining two figures in the paper, which support the last sentence of the abstract. Figure 2 shows that laptop users can take down significantly more words than longhand note-takers, and figure 3 shows that the notes of students using the laptop had significantly more verbatim overlap than did longhand notes. If I had more time, I would have had the groups draw their own conclusions from the two figures—instead, I just told them why the figures were important.

Overall, I liked this activity because it allowed students to think critically about how to design a good experiment about laptop use, predict results that would be convincing, and see the results from the primary source. Although I can’t be sure, this activity may have helped to prevent pushback from students since I showed them instead of just told them why I was enforcing the laptop ban—and hopefully they understand it is for their own good! Next semester, I hope to manage time better to allow for a wrap-up discussion about the study: What did they think? Is the study “perfect”? Is its argument convincing?

If you’re considering a ban of your own and would like the PowerPoint slides I developed, please leave a comment and I’ll send them your way in a jiffy.