Cell Division (Day 1)

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Objective

Students will explore how cells divide and multiply for growth and repair.

Big Idea

In order to multiply, cells need to divide.

Note to Teachers

The Cell Processes unit is part 2 of my Cells 'R Us project based learning experience. Once the students are familiar with the structure of cells, we move on to how cells work. The lessons in this sequence are based on the "need to know's" created by the students (with guidance) for the Cells 'R Us project.

The complete sequence I use for the Cells 'R Us project is:

This mitosis mini-unit uses the web-based inquiry science environment (WISE) developed by UC Berkeley. Before attempting access the interactive with the students, the teacher must have created an account, and started a run of the "What makes a good cancer medicine?: Observing mitosis and cell processes" project (Project Id # 9924). This project mitosis unit helps students understand the process of cell division in the context of learning about cancer.

You can find instructions on how to set up a teacher account and student accounts in my Note to Teachers on the Photosynthesis - a WISE Activity Day 1 lesson.

The WISE platform should be run on Mozilla Firefox with javascript enabled. WISE does not play well when run on Internet Explorer or Chrome.

Hook

5 minutes

To begin this mini-unit on Mitosis, I administer Page Keeley's "Sam's Puppy" Probe (Keeley, P. & Tugel, J. (2009). Uncovering student ideas in science: 25 new formative assessment probes Vol. 3 pg. 125. Arlington, VA: National Science Teachers Association.)

This science probe allows me to assess my students for their prior knowledge on the subject of
cellular division. They give me an idea of where to begin my instruction and what misunderstandings I need to address while teaching.

Once students have turned in their work on the probe, I ask students to remember the three ideas in cell theory and write them on the board as they state them:

  1. All living things are made of cells.
  2. Cells are the basic unit of structure and function in living things.
  3. All cells come from existing cells.

I underline the third statement and ask the class, "Just how do cells come from other cells?" After a brief discussion with the purpose getting an idea of student thinking, I tell the class that we will be studying this process in the context of learning about cancer, using the WISE platform. 

Students will be using their Clock Buddies to form partnerships for the remainder of this mini-unit. 

Explore

40 minutes

Once students are in partnerships, they go get one computer per partnership and log on to WISE. If they have used the site before, they will simply add a new run to their project page (if not, have them follow the sign-up process).

Students work at their own pace throughout the WISE experience. However, there are several discussions that I have during this process:

Activity 1: What is cancer?  - About 5 minutes after students have logged in and started the run, I reconvene the class and tell students to lower their screens to listening height. We then discuss any ideas that were put in their "Idea Basket" under the topic "What do you know about cancer?"

Note to teachers: The discussion about "What is cancer?" can take as long as your students need. When I taught this lesson, I let the discussion run its course, and it was a good decision as it allowed me time to look at their work in the probe (Pacing).

I project the next topic What is mitosis? and have a student read from the screen. I then show this video of mitosis in real time.

Students go back to WISE, add to their "idea basket" and continue on to the next topic. After about another 5 minutes, I again ask students to lower their screens so we can talk about their answers to step 1.5 Why do some cells divide fast and others slow? This discussion is aimed at students engaging in scientific argument from evidence (NGSS Practice 7), and helps them go beyond a superficial answer to a critical thinking application of their knowledge.

I display the next step (1.6: A Definition of cancer), and show this video:

I ask the students to proceed on to Activity 2. Step 2.2 is well aligned with NGSS Practice 4: Analyzing and Interpreting Data, as it asks the students to compare cells in different steps of cell division and draw their own conclusions, even before they can give scientific names to them. In this video you can see how the students attempt to decipher what they are seeing as they attempt to put mitosis in order. In my interactions, I question the students' thinking in order to elicit their evidence based arguments. Later on, they will be able to revise their original placements in light of new evidence NGSS Practice 7: Engaging in argument from evidence.

 

When students reach step 2.6 I hand them the Cell Division XP sheet. This sheet is meant as a note taking guide and is reviewed by me on the spot for completeness and accuracy of the information (student worksheet). Basically, I just want to ensure that the students have the information available to them.

I expect students to complete up to step 2.6 in one session, so students that reach this milestone are encouraged to add ideas to their "Idea Basket" and/or go back to answers that may need some polishing. 

Closure

10 minutes

To close this lesson, I teach the students some hand movements to help them remember the steps in cell division.

In preparation for the next day's activity in the series, I ask the students to do a quick write that ACE's (NGSS Practice 6: Constructing Explanations) the answer to: 

"Cancer cells divide far more rapidly than normal body cells. Using your knowledge about cell division, what do you think is the purpose of chemotherapy and how does it affect cell division?"

These exit tickets (student work) will be used in the Hook of the next day's lesson.