A Hands-On Paper Activity Examining The Relationship Between Hierarchical Levels Of Structure And Of Function
Marc Avery Bellow
How do complex functions arise? How do new properties "emerge" from new arrangements of essentially the same materials? This significant biological question was a theme for the Woodrow Wilson Institute, "Neurobiology At All Levels Of Organization." The question is no less relevant in a beginning biology course. The concept that hierarchical levels of function are related to hierarchical levels of structure grows nicely from a hands-on exercise that I have successfully adapted for students of different ability levels in grades 7 to 12. Students can work individually or in small teams of three or four. They will have an opportunity to discover new emergent properties as they create paper structures to accomplish the following open ended tasks:
remaining suspended in the air for the longest time
traveling the greatest horizontal distance
making the loudest noise
creating a new separate enclosed environment
supporting the greatest weight
jumping the greatest distance
Your students will come up with their own novel solutions, but I suggest that you (or some other individual) construct several examples of the more intricate designs. See background information for origami instructions.
Students struggle with the conceptualization of emergent properties involved in biological systems. For example, how can nonliving atoms even if arranged in complex assemblages, or grouped and bounded by membranes, actually do things that they could not do in their original assemblages. The paper folding exercise will illustrate the relationship between structure and function. Student solutions to the enclosed separate environment task, typically envelopes and boxes, can be used to illustrate how internal environments can be maintained as distinctly different from external ones. "How many sides does this box have?", you ask. After students respond, tell them that the answer is two, an outside and an inside. Following the laughter, or groans, reinforce the importance of discrete localized micro-environments inside the cell where totally different functions can be accomplished. After you challenge your students to give some examples of these in the cell, you would of course refer to the membrane bound subcellular organelles like mitochondria, Golgi, vesicles, vacuoles, etc.
a crane that flaps its wings http://www-personal.umich.edu/~adysart/origami/crane1.html
a frog that jumps http://www.datt.co.jpl/origami/index.html
a huge variety of books on Origami
local library references
Materials for Extensions/Variations
As an extension to this exercise you may choose to make your own paper. (It is rough and of poor quality so that it cannot be used for paper construction.) Bleached and neutralized acid digested wood pulp premixed with a small amount of starch and a still smaller amount of dry wood glue (very little is required / the amount varies and must be determined by trial and error). The wood pulp is floated onto the surface of a bucket of water and a screen is lowered underneath it. A pulpy layer about 1 or 2 mm thick (about 1/5 inch thick ) is allowed to form. The screen is raised underneath the pulp layer which is raised and turned upside down against some newspaper. After some of the water has drained down into the newspaper sheet, an additional sheet is placed over the pulp and it should be pressed flat with a cold iron. Following this, either allow the pressed pulp to air dry or continue to press the layer dry with an iron set to less than 1000 C.
About The Author
Marc Avery Bellow is a teacher of biology and AP psychology at Benjamin Cardozo H. S., 57-00 223 Street, Bayside, NY 11364. The schools fax number is 718 631-7880. He can also be contacted by e-mail at firstname.lastname@example.org