Comparing and Contrasting Meiosis and Mitosis: A Discussion and Analysis

Today's lesson is all about guided discussions as a means to analyze the process of meiosis and connect it to what students already know about mitosis, cancer, and cell division as a general theme. Meiosis diagrams can be quite bewildering for students and they can be quick to shut down; the spokesperson protocol is our main way of navigating a large group discussion in a way that moves efficiently, engages students to interact with each other and the diagrams in order to get to both the details and the larger themes we are discussing together.   

1.  Ask students to take out their textbook and turn to the diagrams of meiosis in your current unit of study.  Alternatively, print out a diagram for students to use.  

• Note:  I like to utilize the textbook here so that we can work on both the concepts of meiosis as well as how to unpack dense academic reading for understanding.  In general, my students use the textbook as a last resort, preferring our slide presentations, discussions, Wikipedia, YouTube, or basically any source other than the textbook!  However, I know that as they continue on in their educational career, textbooks will shift into a primary source very soon and I want to encourage practice with this tool whenever I can.

2.  Announce that today we ail be exploring the process of meiosis and how it compares/contrasts to what we already know about mitosis.

• Note: The key to this lesson seems to be to make it all about adding to what students already know about mitosis.  I tell students that they will not be required to memorize all of the diagrams related to the phases of meiosis; instead, the focus is on how meiosis is different from mitosis and how those difference relate to their different purposes in our body.

1.  Ask students to take a look at the diagrams of meiosis.  Using the spokesperson protocol, ask student groups to discuss one of the following two prompts and share out their responses:  

What do you notice about the phases of meiosis?

OR

How are the phases of meiosis similar to mitosis?

2.  Typical responses will be about how similar the pictures look; that there are sister chromatids, centromeres, a spindle.

• Note: Encourage those observations!  They are key to lowering the stress level of so many drawings and boost confidence for students that they are seeing what is important.

3.  Using the spokesperson protocol, ask student groups to discuss the following prompt and share out their responses:   

How are the phases of meiosis different from mitosis?

The responses you will get will focus on the following important points and if they don't, shift them toward these ideas:

• two sets of phases (meiosis I and II)
• how the chromosomes line up on the spindle fibers
• the number of daughter cells
• the number of chromosomes in each daughter cell

4.  Write a list of the essential vocabulary on the board: meiosis, homologous, haploid.  Ask students to popcorn out the meanings for each word.  Utilize meiosis powerpoint slides for additional student support.

5.  At this point, shift to how meiosis differs between each gonad type, the ovary and the testes.  Show Slide #7 in the meiosis powerpoint slides.  Using the spokesperson protocol, ask students to discuss the following prompt: 

What is the difference between meiosis in men and women?

6.  Field answers and guide students toward the three major differences: # of viable cells, size, and motility.  Most student groups will pick out some but not all of these on their own so your summary is really helpful.

7.  Finish up this lesson segment by reminding students about the purpose of meiosis as shown on Slide #8:  that each haploid gamete (egg or sperm) is intended to join with another haploid gamete to form a diploid zygote.  This is a great time to review the concept of diploid and haploid cells and the terms gamete and zygote.  This is a concept that you will need to come back to over the course of the unit; it is a challenging concept and takes time for students to understand well enough to be able to ask good clarifying questions.

1.  Show this brief video clip summarizing the processes of mitosis and meiosis.

2. Using the spokesperson protocol, ask student groups to discuss the following two prompts:

Name one difference between meiosis and mitosis that you know really well.

Name one thing about meiosis that you still have questions about.

3.  Students should be able to tell you the following:

• Mitosis produces 2 daughter cells, Meiosis 4.
• Mitosis results in identical daughter cells, meiosis does not.
• Only meiosis goes through crossing over.
• Only meiosis has homologous chromosomes sitting on the same spindle fiber which is how/why crossing over happens (in Prophase 1).
• Mitosis produces diploid cells, meiosis produces haploid.

4.  Field student questions to clarify any of the concepts above.  Students will typically need more support to understand the concept of diploid and haploid.  Showing a karyotype and talking about the pairs of homologous chromosomes pictured there helps quite bit.  It is ok if students leave the session with some residual questions about this or any other aspect of meiosis and mitosis; tomorrow's bead lab will help them significantly along on their way to understanding these processes.

5.  Tell students that tomorrow they will be exploring more about the process of meiosis using our bead lab activity!

Depending upon the student group and our content pacing, I often include an addition project after this lesson to help students connect, compare, and recall the processes and purposes of mitosis and meiosis.  The books have taken on many forms over the years: sometimes, they are only about meiosis, other times they cover both processes, and the individual vocabulary or content by page requirements may shift slightly from year to year.  This sample rubric shows a project iteration focused solely on the process of mitosis.  However, the books always share the same basic format:

• A table of contents page
• A MLA formatted reference page
• The use of a narrator/character to tell the story of cell division
• Labeled, colored, handrawn diagrams on each page
• The use of scientific terminology, defined in their own words
• Work shows evidence of time and care
• Work is in collaboration with a partner
• Book contains an job breakdown page showing the work of each partner

I find the book format to be engaging for students and incredibly helpful for processing, constructing, remembering, and contextualizing difficult/new concepts.  By using a narrator, students are forced to use their own words in ways that help them to see and confront any gaps in knowledge while at the same time reducing plagiarism issues.  This year, I assigned the project as an additional, voluntary project rather than a whole class project due to the many other ideas and projects we were working on at the time.  In addition, when I decide the type of book project to do, I am cognizant of the time of year and the project overload students can feel toward the end of each semester as their teachers all add in that type of work.  When students have too many projects to work on, the quality level is lower, both in terms of the final product turned in for grading as well as the overall learning experience for the student.

Check out this short video clip for some of the book projects my students turned in this year!  What immediately sticks out to me is the way students used their narrator/characters to create visually interesting books that presented fairly dry facts in an engaging way.  By using the idea of a children's book, the project encouraged students to shift their language and focus so that the big picture important facts of the process stood apart from small details.

W children's books: https://youtu.be/iE_oiH6VaiU