High School Mathematics-Physics SMILE Meeting
1997-2006 Academic Years
29 November 2005: Arlyn Van Ek (Illiana Christian
Odds and ends
Arlyn attended a recent meeting of the National Science Teachers Association [NSTA] in Chicago, which was great! He brought back these neat odds and ends to share:
13 December 2005:
Chris Etapa [Gunsaulus Academy, science]
Chris showed us various activities that demonstrate wave motion. She obtained the first one at the recent NSTA convention in Chicago. It illustrated how the vibration of insect wings produces sounds. An ordinary pencil eraser was placed at either end of a craft stick, with a semicircular piece of heavy paper attached. The configuration could then be decorated to look like an insect. When a rubber band was stretched around the erasers along the length of the craft stick and the apparatus was swung in a circular motion from an attached string, a sound was made as the rubber bands vibrated while moving through the air. This is a model of how insects make sounds by vibrating their wings in the air. Porter mentioned that, in our rural past, children could get virtually endless and totally free enjoyment by putting a June bug on a string! For a detailed description see the June Bugs website: http://www.cmstory.org/exhibit/plum/june.htm.
Next was a simple apparatus. To a tape of length about 50 cm, she attached (hanging vertically) about 30 plastic straws at equal intervals. By flicking the straws appropriately, she produced a clearly visible transverse wave propagating down the tape. It is a variation of the rather pricey Bell Wave Machine [http://www.physics.ucla.edu/demoweb/demomanual/harmonic_motion_and_waves/waves/bell_wave_machine.html], except that this version is practically free!.
Finally Chris had eight of us stand in a line at the front of the room with arms interlocked. She shoved gently at one end of the line to produce motion, which was transmitted down the line to each member in turn. This is a "human model" of how seismic waves are transmitted through the Earth during an earthquake. Longitudinal, transverse, and shear waves were illustrated by these august performers!
Neato! Thanks Chris, and thanks to your valiant team.