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3rd Grade – Pendulum Swings

Posted in 3rd Grade

Galileo is one of my heroes. Astronomy and telescopes, motion and gravity,

A small washer, or two, a purple string, and presto, a pendulum.

Measured in length from the center of the hole to a red mark on the string- 30, 40, 50 cm.  Longer and shorter ones, too.  Tape the red mark to something sturdy- a table or doorway.

Counting the cycles, over and back, students recorded between 15 and 50 cycles per 30 seconds.   We recorded length vs. cycles on a chart.  Different teams with the same length pendulum sometimes recorded the same number of cycles, and sometimes different numbers. Suggestions were made about repeating the ones that didn’t fit the pattern we observed.  Students tried to write a succinct rule describing the pattern.  The most poetic: The longer the string, the slower the swing.

The following week some classes wondered about another experiment: the same length of string and different numbers of washers.

Here’s the challenge…

in the tradition of Galileo, make a pendulum with the proper length to make a good time-keeper,

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