Friday 1/25/13

EQ: "Why are cells so small?"

VOCAB:

HOMEWORK: none

CLASS RECAP:  Today students cleared out their binders from the first two marking periods.  Then we reviewed the multiple choice section of the mid-term.

We then discussed the next unit we will be learning about.  Cell growth and Division.  Students were challeged with two questions:

1) Why must cells divide?

2) Why are cells so small?


As students thought about answers to these questions, they watched the following clip of how a human develops from a one celled organism to an infant in the womb.
 Students took notes in their Daily Science journals that:

1) Why must cells divide?
     - so the organism can increase in size
     - so the organism can develop
     - so we can be multicellular
     - so the organism can have different types of cells (ie, brain, skin, liver)
     - so we can replace dead cells  (ie, blood, skin)
     - so we can heal cuts/wounds
   
2) Why are cells so small?
     - so organisms can have many types of different systems containing different types of cells
     - we wouldn't be as specialized/complex if we had large cells
     - efficient surface area to volume ratio.  

Then students observed a demo involving water balloons that represented cells.