Germaphobes, Beware!!!!

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Objective

Students will examine the characteristics and structure of bacteria and understand how they are like and unlike eukaryotic cells in both structure and function.

Big Idea

Bacteria have unique qualities.

Warm-Up

5 minutes

Warm-up: Where can germs be found?

Allow 2-3 students to respond to the question then ask  a 2nd question, “What are germs?”  Follow with a 3rd question, “Are germs living?” 

Use the technique of progressively increasing the complexity of subsequent questions to the initial warm-up question as a means of assessing the depth of students prior knowledge.  Use the  assessment to tailor the lesson to the class needs.  If the students are unable to answer the questions that are asked after the initial warm-up question, take 3-5 minutes to review concepts so that the students will be “up to speed” before moving into new content.

Look for students to identify that both viruses and bacteria may be called “germs”.  Once this is established, ask students to explain if viruses and bacteria are the same or different.  Without teaching the content that will follow later in the lesson, ask students to give one reason why viruses and bacteria are not the same.  Look for students to identify that bacteria are living because they are made of cells and that viruses are not living because they are not made of cells.

Use of progressive questioning and academic discourse are  great tools to build on concepts and prepare students for new material. 

After this brief discussion, show a brief  video clip that introduces several of the concepts related to bacteria.  Note:  I really like the work of this particular producer because the clips are short, visually stimulating and they include written narrative that helps students learn before I even begin to teach.


 

 

Introduce New Material

30 minutes

Introduce the content specific vocabulary for the lesson: prokaryote, eukaryote, symbiosis, cytoplasm, binary fission, antibiotic, and microscope

Instruct students to add the bolded terms to their Vocabulary Map.  Remind students that the bolded terms include Greek or Latin root words, prefixes or suffixes.  A preview of the terms is all that is needed at this time.  Teach the terms explicitly when they are used within the context of the lesson.

Explain that students will first  participate in a listening activity listen for ten minutes on the Kahn Academy bacteria lesson.  Starting with the Ipod listening assignment allows for the use of different learning experiences that address different learning styles of students.  I consider this type of listening activity before actually teaching somewhat of a process of “preparing the soil” for the instruction that will follow. 

As mentioned in a previous lesson,Virus part I, use a iPod assignment sheet to issue electronic devices efficiently during class with little use of instructional time.

Display the Ipod listening activity and explain that the assignment requires students to write ten facts and draw at least one diagram based on the information learned from the listening activity.  Inform students that the work will be collected at the end of 15 minutes. Use a timer and collect all work when the time period ends.  

After completing the listening activity, share specific content points about eukaryotes and prokaryotes.  Instruct students to take notes using a previously taught note-taking format.  Provide highlighters for students use as they take notes and guide them in what points they should highlight in the notes. 

Explicitly teach the terms, eukaryote and prokaryote.  Remind students  “eu” means true, “pro” means “before”, and “kary” means nucleus.  

Walk around while providing instruction to ensure that students are writing accurate information in their notes.  Acknowledge those students who are actively demonstrating taught skills such as use of highlighters and adding to the notes by writing additional information in the margins. 

This type of intentional recognition of positive behaviors can be a great motivator for students who are off task. Hearing praise of another student's desired behavior acts as a reminder of what is expected.  This can sometimes encourage students to get on task without having to say anything directly to them. 

Along with open acknowledgement, look for and redirect students who have fallen behind the group or who have not written anything on their guided notes form.  Walking around is a great tool for proximity control of students who tend to stray off task.


Guided Practice

5 minutes

Display a Prokaryote and Eukaryote comparison, which consists of a set of twelve descriptions.  Explain that the task requires students to identify each description that fits prokaryotes, eukaryotes, or both. 

Model how to complete the task using the Think aloud strategy as you consider each description and determine if the description fits prokaryotes or eukaryotes.  If the description fits eukaryotes, write an E next to the description.  If the description fits prokaryotes , write a P next to description.   This immediate review helps students reinforce the concepts just learned.

Emphasis your reasoning as you select the choice for each description, giving students a chance to hear the correct answer, but also why you did not choose the alternative choice.  After modeling your thought process for the first 3-4 descriptions, ask students to guide the work for the remaining descriptions.

Independent Practice

10 minutes

Instruct students  to create a graphic organizer that compares and contrasts prokaryotes and eukaryotes.  Provide markers and colored pencils for students. 

Inform students that they do not have to use a classic Venn diagram to complete this assignment.  Encourage students to create their own format that shows both similarities and differences between the two.  The intent of giving students a target without dictating “how” they are to do it allows students to create a work product that meets the task requirement without prescribing how to do it.

To ensure that all students will be able to complete the assignment, quickly review the purpose of a Venn diagram, which is comparison/contrast graphic organizer.  Explain that the section of the diagram where the two shapes intersects should be used to notate characteristics about the two things that are the same.  This type of quick review lessens the inevitable questions and lack of understanding that some students will have.

Consider sharing old student work samples with the class before releasing them to work independently.  However, use caution when sharing work examples because it sometimes limits students ability to develop their own ideas about how to complete an assignment.  

The first student work shows a student who embraced the opportunity to make it the Venn diagram represent his creativity. The second student work shows a student who was also able to show understanding but who chose the traditional Venn diagram format with no use of color.  Both demonstrate understanding and mastery of the concepts. 

Lesson Close

5 minutes

Ask students to consider and write a explanation for why the words eukaryote and prokaryote are good terms for the organisms they describe. Build on this first response and ask them to also respond to a second question, “What do these terms suggest about the order of evolution of these organisms?”

Distribute post-it notes and instruct students to place their responses on a sheet of chart paper in one of three labeled sections on the chart paper:

  • I fully understand the differences between prokaryotes and eukaryotes,
  • I have a fuzzy understanding of the differences and similarities between prokaryotes, and eukaryotes, and
  • I do not understand the differences between prokaryotes and eukaryotes. 

After class ends, pull the post-it notes  by section and look over the responses:

  • For the first question, look for students ability to accurately convey that prokaryotes do not have a nucleus and eukaryotes do have a nucleus.  
  • For the second question, determine how many students were able to connect the order of the evolution of these organisms to the differences between them.  
  • Also, use this simple chart to compare how accurately students were able to identify how well they achieved the learning target established for the day with the accuracy of the responses that are shown on the post-its.  

Ideally, students who answered correctly should have also placed themselves in the group "I fully understand the differences between prokaryotes and eukaryotes", etc...

Use the information to guide the review and/or warm-up question for the next day. Follow up with those students who are found to not have answered the questions correctly and who were not able to correctly self-identify their placement on the learning chart.  This is important because students need to be able to self-assess accurately in order to guide and build ownership of their learning experiences.