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.

Photo of Staphylococcus aureus

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.

Antibiotic resistant beads

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.


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

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390 Responses to Antibiotic-Resistant Bacteria: A Simple, Realistic Lab Activity

  1. Cassy says:

    Great article! I would love a copy of your worksheet if you’re still sending them!

  2. Nick Grabemeyer says:

    I would also love a copy of the activity write-up! Thank you!

  3. Jamie L Burns says:

    Could I have a copy of the activity too? Thank you.

  4. Leslie Pcolinsky says:

    Hello – Would you be able to share the activity with me? Thank you!

  5. Laura says:

    I would love a copy!

  6. Krystal Wattley says:

    Please send a copy of your activity! Thank you!

  7. Carol says:

    Can you please share this activity with me? I love this idea for my nonmajors biology course!

  8. Danette Koanui says:

    Could I please have a copy?! Looks awesome!

  9. Heather Pfannenstiel says:

    Could you please send me the hand out you reference in the article? I would love to try this in one of our Introductory Biology labs.

  10. Would love a copy of this… It sounds great.

  11. Susan Jackson says:

    This activity is intriguing. I appreciate that you modified an unclear step in the activity. I would love a copy of the lab.

  12. Brianna says:

    Would love a copy of this please!

  13. Isabel Canizares says:

    I would also love a copy!

  14. Liz Johnson says:

    Hi there! Love this activity – may I please have a copy? Thanks!

  15. Jill says:

    Hello! May I please have a copy? Thanks!

  16. Claudia Arakelian says:

    May I please have a copy, my students would love this!

  17. Craig says:

    Thanks for posting this article. I would greatly appreciate a copy of the activity to try this fall with my students.

  18. Celia M says:

    Hi. I would love a copy as well. Thanks for sharing!

  19. Please send me a copy of your activity. Thank you so much.

  20. Melissa says:

    Hello, could you please send a handout to my email as well? Thank you!

  21. Molly Smith says:

    Hi. I would really appreciate a copy of your activity. I’m always looking for new things to try with my non-majors biology students.This sounds great. I intend to use it in the microbiology class I teach, also. Thanks.

  22. Stacy Sinibaldi says:

    I would like a copy of your handout. I’d like to try this activity with my high school biology class.Thanks!

  23. Brian K says:


    I’d very much appreciate a copy of the handout you created. Thanks for all you do to help disseminate strategies to teach biology engagingly!

    Kind regards,

  24. Eve Harrison says:

    Please email me a copy of this activity…
    I have down something similar through a Wards Kit, but this one looks more “striking”!

  25. Daniel A says:

    I would appreciate a copy so I could try it in my high school biology class.

  26. BKreb says:

    hello I would appreciate a copy so I can try it with my high school biology class.

  27. Bethallyn Parker says:

    I would love a copy of the lab handout, please!

  28. Tara says:

    I’d love a copy of the handout! Thanks!

  29. Emily French says:

    I like your activity! Could I have a copy of your lab handout?

  30. Jason Flora says:

    Is there any way to get a copy of this activity? It looks great for my freshman!

  31. mishmash467S says:

    Hello! I enjoyed this article. I see it was dated back in 2017, is it possible to get a copy of the activity? This looks great for our homeschool biology course.

  32. Kelley Brockinton says:

    I would love a copy of the handout and table

  33. Lehua Werdel says:

    Just read your article. If you are able, please send a copy of your activity. Thank you!

  34. Jenny Ruby says:

    Would love a copy of your willing to share!

  35. Rob Beidler says:

    Would you be able to share a copy? I’d love to use this to do an antibiotic resistance lab. How long did this generally take?

  36. Rob Beidler says:

    Would you be able to share a copy? I’d love to use this for a lab next week. Thank you!!

  37. Karin Montemayor says:

    Would love a copy of this lab, looks great.

  38. Robin Rathman says:


    I would love a copy of this antibiotic resistance modeling activity. Thank you !

  39. Sheryl Juenemann says:

    Looks like a great activity! Could I please have a copy of the handout?

  40. Monica Lewis says:

    I would like a copy of the write up for the lab.

  41. Nicole Benenati says:

    This activity sounds great. Could I have a copy please? Thank you!

  42. john yanni says:

    love your idea of using beads…could you send a copy? thank you

  43. Christina Garcia says:

    Love this activity! Can I get a copy?

  44. I would also love a copy of this activity.

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