Monday, November 11, 2013

Engineering Cell Division - a NGSS lesson

My passion right now is inquiry and really trying to develop labs that emphasize THINKING processes, getting kids to ask good questions and finding ways to answer them.

I am also using the NGSS (Next Generation Science Standards) to reframe how I teach. For example; for years, I have used the traditional "hands-on lab" of pipe cleaners to teach mitosis and cell division. With the new standards the focus is not on rote memorization of the phase names. Check out HS standard HS-LS1-4.

HS-LS1-4.Use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms. [Assessment Boundary: Assessment does not include specific gene control mechanisms or rote memorization of the steps of mitosis.]
At first I was broken hearted..I love teaching the phases of the cell cycle. But in reality, does every kid need to know the WORDS, Prophase, Metaphase, Anaphase etc... to be successful in life? No. So I rewrote the lab to focus more on problem-solving...and took an engineering slant to it. I just had a group of middle and high school boys complete the lab, it went extremely well. And the bonus? The following weeks, they still had retained all the "big picture" ideas from the lab.

[Free download available at the end of this post.] 

Setting up the Engineering Cell Division Lab


I set out a variety of materials including: (But really, just gather up as much junk as you want, the kids will be creative in how they use them.)

  • twine
  • pipe cleaners 
  • playdough
  • craft pom-poms
  • clothes pins
  • beads, pennies
  • other stuff


The way the NGSS has made me rethink the way I teach is to use models more, and to really drive home the Cross-Cutting concepts. Before developing a model, I have students brainstorm both structural and functional barriers that a cell has to overcome.  Here is how I word it in the lab: 


1.     What are the major structural and functional barriers a cell must overcome? Then brainstorm some ways the cell might overcome the barrier.
a.     Structural barriers refer to the cell parts
b.     Functional barriers refer to the ability of the cell to work and do its job

I have them work on this chart as they brainstorm barriers and then solutions. Don't be too hung up on the solutions column just yet. Sometimes the students need to "play" with the materials to determine what has to happen in order for a cell to divide.  I've included a few students may come up with. 


Structural
Functional
Description of Barrier
(Design problem)
Possible Solutions

 X

 There must be enough genetic material for 2 cells

 At some point the DNA must double...Can cell be "working" when this is going on? 
 X

 The genetic material is protected inside the nuclear membrane. How does it get out? 

 Nuclear membrane must pinch off (or dissolve). 
 X


 Size issue: If a cell divides; cutting itself into 2; and the next generation does the same, the cells will get smaller and smaller.

 At some point, the cell must grow before it divides. 

 X

 Organelles must also be divided. (Does it matter how many mitochondria each cell gets?) 









Then, once students have addressed the engineering challenges a cell faces in order to replicate, I have a section in the lab called....

Play Time


I wished I would have learned earlier about the power of play, even with middle and high school students. Unfortunately, school has squeezed out much of the natural curiosity that students have, but if you allow (sometimes force) them to be creative, they will...and they'll enjoy it!   



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