Bacteria... Friend or Foe?

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Students will examine the good and bad aspects of bacteria and understand that not all bacteria are harmful; some are actually helpful.

Big Idea

Bacteria are a the "frenemies" that you can't live without.


5 minutes

Begin the lesson with a Warm-Up which displays an image of a cell. Based on the information shown, ask students would scientists classify this cell as a prokaryote or a eukaryote? Ask students to identify the labeled parts and explain the rationale behind their answer choices. This question serves as a review of the content taught the previous day.  Look for students to explain that this cell is classified as a prokaryote because the cell does not have a nucleus. 

Ask students if they think bacteria can be both helpful and harmful.  Allow students to engage in academic discourse around this question. Remind them to use the sentence prompts in their responses.

Do not correct any thinking at this time because the intent is to allow the misconceptions to rise to the surface.  You will have a chance to address any misconceptions during the introduction of new material. However, if the misconception is related to something that you have already taught, address it at the point that it is raised so that students won’t build new knowledge on incorrect information.

Introduce New Material

20 minutes

A common misconception is that all bacteria are bad for you. Some bacteria are harmful and even lethal, but the majority of them are completely harmless, and some are highly beneficial to humans.  Introduce the term, probiotic and ask students to consider what this term might mean based on the root words that they are able to identify in the term. 

Allow students to use their Vocabulary Map and the root words they have documented as a resource.  Look for most or all students to identify “bio” as a root word that means living/life. To lead them to determine the meaning of “pro”without answering for them, ask students, “what is the opposite of “con”?, which means against.  Look for  students to indicate that “pro” means “for”. 

Close this short explicit vocabulary instruction by making sure that all students understand that a probiotics are bacteria that are good for you, or “pro/for” living.

Today’s content involves watching a video to explore the good and bad sides of bacteria. Note: Discovery Education is a free site with great resources for teachers.  You have to create an account to access this and other video clips.

Inform students that they will need to take notes using the Cornell notes format that was taught in a previous lesson to document key points.  It’s important to require students to engage in an activity when watching video clips in class. 

Because video clips that are selected for inclusion in the lesson plan are included with an instructional intent, teachers should not lose that significance by releasing students from any responsibility while watching.  The intent of having students write notes or answer questions is to increase the chances of them creating a written record of the key concepts shown in the video clip.  

Make it a practice to pre-watch video clips before showing them to students.  This allows for the identification of key points in the video where the video can be stopped and emphasis made or extension of a concept or thought.

For example: at 7:20 min you can pause the video and ask, "What organisms can be found in extreme environments?" and have a short discussion.  This kind of activity provides opportunity for greater interaction during videos, as well.


Guided Practice

5 minutes

Using E. Coli as an example, model how to use the computer to research and cite specific facts about this bacterium.  Share your thought process for determining if this bacterium is a “Friend of the State” or “Most Wanted”.  Be sure to identify specifics like: where is it likely to be found, who is most likely to be infected, etc…  Think aloud as you consider the facts and make a decision as to the category in which you would place the bacterium.  Show them how you correctly cite where you collected your information, using MLA format:

Last name, First name. "Article Title." Website Title. Publisher of Website, Day Month Year article was published. Web. Day Month Year article was accessed.


Cain, Kevin. "The Negative Effects of Facebook on Communication." Social Media Today RSS N.p., 29 June 2012. Web. 02 Jan. 2013.


Independent Practice

20 minutes

Present the performance task, “Bacteria Wanted Poster. Explain the assignment and share the rubric that students should use to guide completion of the task.  Provide 8x 14 or larger paper, markers, and colored pencils. 

As part of the preparation for this lesson, have the PCs already placed on student desks to expedite students moving quickly to the assignment after you have given explicit instructions. 

Instruct students to identify a bacterium of their choice and find their own resources or provide a list of bacterium and resources that students can use as a reference.

It is likely that students will not complete this task during class. However, allow students the chance to begin the assignment in class so they will be able to ask questions and seek assistance, if needed. Allowing students to begin work in class also allows for an assessment of students' understanding of the task and how well they will be able to correctly complete the task at home.  

I was very pleased with the creativity of the student work and found that many students went beyond the criteria noted in the rubric and crafted some very creative work products:

  • Student work1 reflects one student's idea of how he wanted to portray clostridium. 
  • Student work2 shows how the student organized facts about gonorrhea in a visually appealing fashion.  
  • Student work3 shows how a student chose to portray Legionnaire disease,  and
  • student work 4 shows how the student chose to go above and beyond to create a burned edges wanted poster on MRSA.

Teaching students how to cite sources in the science classroom allows students to strengthen their writing across the curriculum skills.

While the work includes citations, the formatting of the citations are not reflective of what is the appropriate citation methodology.  A review of the formatting for student work1 citation, student work2 citation student work 3 citation and student work4 citation show that students need further practice citing sources.





Lesson Close

5 minutes

Quickly ask each student to share one fact from the notes that they wrote during the video as a verbal “ticket out the door”. Encourage students to extend someone else’s thought if they had the same fact on their paper.  Listen for accurate information being shared by students and correct any misinformation that is shared.  This is an effective formative assessment that allows you to determine if students met the learning target for the day.