# news & tips

A collection of helpful articles on teachers and teaching

# Clocks in the Classroom

In January many students, and teachers, will believe that time moves more slowly. Not true but the short days and the cold weather often plays tricks with our sense of time. That opens an amazing teachable moment for science.

The measurement of time is a fascinating history lesson.

If you ask your students to tell you the approximate time without looking at a clock there is some interesting data to think about. How accurate are the student guesses? Are they all off by a similar amount? That question is a good springboard for thinking about and exploring the science of timekeeping.

When you think about it a clock is a pretty amazing blend of science and math.  How did early pendulum devices chop up an hour into minutes? How did they figure out the gear ratio to make a mechanical clock that keeps accurate time to the second? There are a thousand questions. I would love to have a group of students brainstorm their questions on the board and work from there.

If you teach a clock or time unit you have to let the kids experiment with a water clock. One of the earliest timekeeping device used dripping water to measure the passage of time. These devices are easy to build and have rich applications in math for elementary students, engaging math for secondary kids if you ask them to build devices to a specific set of standards. Lots of web sites will give directions for the construction and some hints for lesson plans:
http://www.wisegeek.com/what-is-a-water-clock.htm

The old PBS series “Newton’s Apple” has an archived set of lessons:
http://www.darylscience.com/Demos/Clocks.html

The largest water clock in North America is at the Children’s Museum of Indianapolis.
http://www.childrensmuseum.org/themuseum/icons/waterclock.htm

One teacher I worked with created a “Festival of Time”. This unit blended social studies, writings about time, a time capsule and a construction contest in which the students had to make a clock that would keep time to an accuracy of + or – 2 minutes in a one hour time block. That rate is not very accurate by our current standards but an excellent activity for an entire school. The judges, who had to sit, watch and judge the timing devices were math and science students from the local high school. The winning device was a water clock constructed from soup and coffee cans that sat on a stair step of bricks. The device was not elegant by artistic standards but the young student who constructed it had built it, timed and tested the device and learned a great deal in the process. Not bad for a day’s work.

Another teacher used pendulums and sent the students off on a variety of investigations involving the regularity of swinging pendulums. The culminating event of this activity was the construction of a Foucault pendulum from the 3rd floor stairwell in the school. A Foucault pendulum is a device that demonstrated the rotation of the earth. There is one at the University of Louisville that has a great web site and explanation.
http://www.astro.louisville.edu/foucault/index.html

So, as the days get longer and the kids become more restless we might not be able to beat time, but we can certainly put it to good use.