To develop an understanding of the characteristics and diversity of microbial life.
This lesson uses the book: The Invisible Kingdom: From the Tips of Our Fingers to the Tops of Our Trash, Inside the Curious World of Microbes by Idan Ben-Barak (Basic Books, 2009). This book was one of the winners of the 2010 AAAS/Subaru SB&F Prize for Excellence in Science Books (you can read about this prize at: Book Award).
Depending on the level of your students, the book can provide a good introduction to important topics in the study of the microbial world. Ben-Barak discusses a variety of topics ranging from biofilms, antibiotic resistance, horizontal gene transfer, and the value of hand washing, to name a few. He loosely defines microbes to encompass bacteria, archaea, fungi, and protists. He also considers forms from the untidy border of life itself: viruses, transposons, prions, and Tasmanian devil tumor cancer. The fact-packed chapters reveal how microbes develop, behave, and evolve and how life on Earth would cease without them. "Bonus tracks" offer additional fascinating stories, such as that of the "corrupted blood" epidemic in the virtual World of Warcraft. The author often mentions how scientists have developed our understanding of microbes, and he frequently raises unanswered questions and conflicting interpretations.
This lesson can be used along with these Science NetLinks lessons for the study of microbes in the classroom:
- The Ecology of Your Skin 1: Bacteria that Live on the Skin explores the concept of interdependence of life in the context of our relationship with bacteria.
- The Ecology of Your Skin 2: The Microbial World is an Olfactory World introduces students to the olfactory world of our bacterial symbionts.
- In The Ecology of Your Skin 3: The Body Food Connection, students perform an exploration of bacteria in milk to see how they can get cheese-like results from body bacteria in order to gain a deeper understanding of the interactions between organisms.
Below are some common misconceptions that students might have about microbes. Keep these in mind as you conduct this lesson.
- Students may have difficulty conceptualizing microbes as agents of change (example: microbes and decay—they often think decay is an inherent property of the object itself rather than a transformation that results from an action of the microbes).
- Students may think that all microbes are bad and/or equate most microbes with disease.
- Students may think that all diseases are caused by "germs."
Microbial Mythology from Kenyon College discusses these and other misconceptions as well as ways to combat/address them.
Note: This lesson utilizes a reading log that can be used for students to write down reflections as they read. If you use a different reading log format, if students in your class already keep reading notebooks, or if you want to focus on a particular aspect of the book, feel free to adapt this or to use your own template.
Teacher Preparation: To prepare for the lesson, you may wish to visit Microbe Library. This site contains over 300 high-quality, peer-reviewed images, animations, and videos about the microbial world for educators, primarily at the undergraduate level. Access to the resource is free, but you will need to register to use the site.
One of the most persistent misconceptions that students, and many adults, have about microbes is that they are "bad." Begin the lesson by writing the phrase "Microbes: Good or Evil?" on the chalkboard. Ask students to respond to the phrase in order to determine how many of your students exhibit this misconception, and to what extent. Accept all student responses. After you've completed the lesson, you can revisit the question and ask students to reflect upon the effect that reading The Invisible Kingdom has had on the way they perceive microbes.
Then, students should use The Invisible Kingdom student esheet to go to and view the Savage Yard video segment about microbes. After students have watched the brief video segment, discuss why Savage Yard host Bob Hirshon says that we owe our very life to bacteria.
The rest of the lesson will mostly consist of out-of-class activities. Students should read the book and prepare an Invisible Kingdom Reading Log, which should be collected by you and graded.
The reading log for this lesson is a variation of a double-entry note log. Using the log, students will select passages to highlight in their log that strike them as significant. The reading log provided contains guiding statements called Idea Strands, but you can choose to focus student reading on topics that relate to science learning goals that are being explored in the classroom. For example, students can be asked to look for passages in each chapter that pertain to some of these ideas:
- Where do bacteria live?
- How long have bacteria been around?
- What sets bacteria apart from other organisms?
- How do bacteria reproduce?
- What do bacteria do to living things?
- What do bacteria do to the environment?
- Are bacteria harmful or beneficial to us?
Please refer to the Introduction to Reading Guides if you are not familiar with this note-taking strategy.
After they have finished reading the book, students should complete one of these activities (instructions for these can be found on the student reading log):
- Create a commercial for the book in a video or brochure format
- Make a PowerPoint presentation about microbes
- Interview a bacteria
- Write a graphic story using information from the book
You can collect and grade the reading logs. Make sure that students have identified an idea strand and have related it to information found in the chapter. Satisfactory student work will have succinct summaries of the chapter and one or two sentences relating the chapter to at least one selected idea strand. Exemplary student work will relate multiple idea strands to each chapter and also make connections from one chapter to the next.
Since the project ideas utilize a variety of creative formats, you may wish to make a rubric that students can use to guide their work. Consider developing a rubric for assessment of the essay. There are several resources on the Internet that describe the use of rubrics in the K-12 classroom, a few of which are highlighted here.
To learn more about rubrics in general, see Make Room for Rubrics on the Scholastic site.
For specific examples of rubrics, more information, and links to other resources, check out these sites:
Finally, you can go to Teacher Rubric Makers on the Teach-nology.com website to create your own rubrics. At this site, you can fill out forms to create rubrics suitable for your particular students, and then print them instantly from your computer.
To bring the content of the book more alive in the classroom, it is recommended that the lesson be accompanied by a hands-on activity such as those found on Mircrobes in Action. We would recommend a couple of the activities in particular:
- Something Rotten in the Vegetable Bin demonstrates that a bacterium called Erwinia carotovora is the organism that causes a plant disease called "soft rot." This laboratory is a model for the study of infectious disease; however, this organism is harmless to humans.
- Is Bleach a Good Disinfectant? is an activity in which students determine the concentration of bleach that kills E. coli.
If desired, the book can be assigned as independent reading without using the reading log. You can use the SB&F Book Club Guide: Invisible Kingdom: From the Tips of Our Fingers to the Tops of Our Trash, Inside the Curious World of Microbes for ideas on discussion questions and background information.
These Science Updates can also be used to learn about microbes: