Cell Division

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Objective

Students will know that mitosis produces diploid daughter cells and meiosis produces haploid daughter cells.

Big Idea

Mitosis produces cells that are identical to the parent cell.

Warm-Up

5 minutes

Warm-Up: Which organelle plays a role in cell division?

Remind students that they learned about cell organelles in a previous lesson, xxxx.  It allows students to recall what they know about cell organelles in order to activate that prior knowledge in order to apply it to what they will learn in today’s lesson on cell division.  Ask students to discuss their answer choice with a seatmate.  Ask for a student to share the answer.  Confirm that centrioles play a part in cell division.  As a review of organelles, ask students to also explain the function of the lysosome, nucleus, and ribosomes.  This type of quick review is helpful to help students retain information over time. 

Inform students that they will learn about cell division in today’s lesson.           

Introduce New Material

20 minutes

Begin the lesson by introducing the vocabulary associated with the lesson:  somatic cell, cytokinesis, haploid, diploid, chromosome, daughter, interphase, mitosis, meiosis, binary fission

Say each word aloud and ask students to repeat the term after you.  Clap out the syllables for the terms with 3 or more syllables.  This helps students hear the word parts of more complex words so that they can pronounce them correctly. 

Instruct students to add the bolded terms to their Vocabulary Map. Remind students that the bolded terms contain prefixes, suffixes, Greek or Latin root words.  Provide explicit instruction of each term when it arises during the course of instruction.

Inform students of the learning targets for this lesson:

  • I can explain the process by which prokaryotic and eukaryotic cells produce offspring cells.
  • I can calculate the diploid and haploid chromosome number for an organism.

Begin the lesson with students engaging in an Ipod listening assignment on Kahn Academy. Instruct students to select the Kahn Academy Biology I series Lesson 8, Mitosis, Meiosis and Sexual Reproduction.  Require students to write 10 facts and draw one illustration, using information gained from the lesson.  Display the Ipod listening assignment on a LCD projector as you explain the task.Set the timer and allow students to work independently.

Starting with the Ipod listening assignment allows for the use of multimodal learning experiences that address different learning styles of students.  I consider this type of listening activity before actually teaching somewhat of a process of “prepping” for the instruction that will follow. 

A review of the Ipod listening student work shows that students are able to gain a significant amount of information from a short listening activity.  The movie clip of a student's comments about why she enjoys the listening activity also shows how the activity meets different student styles of learning.

Refer to the Virus part I lesson for the process I use to issue electronic devices efficiently during class with little use of instructional time.  

After the listening activity, distribute guided notes and spend about 15 minutes sharing specific content points about cell division.  Display visual information as you instruct and ensure students take notes using guided notes that you have provided or use a note-taking strategy that you have taught. 

For this lesson, the guided notes are displayed as a cell cycle graphic organizer.  Varying the format of guided notes helps engage students by using a less typical note taking format. Use of graphic organizer for note-taking also allows students to see that information can be captured effectively using different formats. So,  when they have to take their own notes without the aid of guided notes, they may be more inclined to use any format that works best for them.

It’s a good idea to provide highlighters for students to use as they take notes and guide them in what points they should highlight in the notes. 

Walk around as you teach the pertinent information to ensure that students are writing accurate information on the guided notes that you have provided.  Openly acknowledge to the class, those behaviors by students that demonstrate taught skills such as use of highlighters and adding to the notes by writing additional information in the margins.   This type of intentional recognition can be a great motivator for those who are off task.  The reminder of what you expect can sometimes lead them to get on task without you saying 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 may tend to stray off task.

For visual learners, consider drawing a circle to explain the parts of the cell cycle and instruct students to do the same on their papers:

  • Dissect the circle into parts, showing that the largest part of the circle represents Interphase, with it consisting of G1, S and G2 stages.
  • Represent the next portion of the circle as M-phase, with it consisting of prophase, metaphase, anaphase, and telephase.
  • Represent the remaining portion of the circle as cytokinesis.

Guided Practice

5 minutes

Stop at various points during the instruction and model skills that students are expected to know or do. After discussing the difference between haploid and diploid chromosome numbers, allow students to practice calculating both numbers.  If you have white boards available, use them for this formative assessment.  For example, display this problem:

A fly has 12 chromosomes in its body cells.  How many are in its:

  1. Sex cells _________
  2. Brain cells ________
  3. Sperm _________
  4. Liver cells_______
  5. Zygote (fertilized egg) ________

Use a “think aloud” to model how students would think in order to correctly answer the first problem.   Be sure to use the content related vocabulary as you think aloud to reinforce the vocabulary instruction related to the lesson.  Instruct students to work together to answer the remaining four problems.  Walk around to listen and observe students as they work on the whiteboards.  Allow 4 groups to share their answers with the class.  If errors in the calculations are noted, spiral back and re-teach the difference between haploid and diploid cells.

Independent Practice

20 minutes

Display and distribute a Mitosis and Meiosis Chromosomes calculation activity.  Instruct students to complete the two tables and create a graph to display their calculations. Instruct students to work independently to complete this formative assessment.  Walk around to observe how well students are able to complete the assignment independently. Look for students to demonstrate an understanding that the sex cell chromosome number is half the body cell chromosome number. Provide guidance and assistance as needed to students.

The student work samples that are included demonstrate that students are able to correctly calculate the haploid and diploid chromosome numbers.  Student work 1, student work 2 and student work 3 all show that the students grasp the concepts and are able to perform the calculations to determine the correct chromosome numbers for each type of cell, thus showing mastery of the concepts after instruction.

Expect that there will be those students who are not able to readily grasp how to perform the calculations so be prepared to work in small groups with those students.  Student work 3 shows that the student performed the math on the page to calculate some of the values.

The student work also demonstrates that the students were able to display the information graphically.  Because many students struggle with depicting data, it's a good practice to have them depict data graphically whenever possible.  This reinforces their ability to determine how to display data correctly.

Close

5 minutes

Select 2-3 of the problems to review whole group before students are dismissed.  Ask for student volunteers to provide the correct number of chromosomes for each and explain why how the answer was derived.

Ask students to show how many agree or disagree with the answer provided by the student volunteer.  If there are differing opinions about what the correct answer is, take the time to quickly review how to calculate the number of chromosomes for sex cells and body cells.  Allow for questions before students are dismissed.