Portable Sundial
Students examine sundialsCopyright Wikimedia Commons http://commons.wikimedia.org/wiki/File:Horus_Sundials_Portable_Horizontal_Sundial.jpg
Students investigate the accuracy of sundials and the discrepancy that lies between "real time" and "clock time." They track the position of the sun during the course of a relatively short period of time as they make a shadow plot, a horizontal sundial, and a diptych sundial. (The activity may be abridged to include only one or two of the different sundials, instead of all three.)
This activity focuses on the importance of accuracy in time measurements that are used today in a wide variety of instruments such as cell phones, computers and GPS navigation systems to synchronize their functions. Improving precision, be it in component size or digital time measurement, is a design criterion that engineers address everyday.
- How the sun moves across the sky.
- The difference between "clock time" and "real time."
- How to find geographical north.
- Terminology, such as solstice, equinox, etc.
- How to make a sundial, what makes it accurate, and what skews the time it tells.