In collaboration with another school north or south of yours, rnuse the method of Eratoshenes to determine the circumference rnof the Earth.

Make observations and use available data and simple calculations to correlate observations and data in the characterization of stars. In this activity, the distances to bright stars are calculated. The apparent brightness of these stars is then adjusted for distance to see which stars are intrinsically bright and which only appear bright because of their proximity to Earth.

Detect patterns and uncover cause-and-effect relationships using the Mapping For Everyone web toolkit (http://www.esri.com/mappingforeveryone). By analyzing median age, home value, population change, household size, and other variables, you will be thinking critically and spatially while comparing differences between your neighborhood and others around the country.

Astronomers build larger telescopes not only to collect more energy but also to resolve finer detail in the objects to be studied. While groundbased optical telescopes with "filled" apertures of up to 10 m have been built, and 30 m and larger-aperture designs are being studied, another method of observations permits equivalent apertures spanning tens to hundreds of meters to be used. Radio astronomers have used these instruments, called interferometers, for decades, with equivalent apertures spanning thousands of kilometers.

Demonstrate the wave nature of light by projecting interference patterns. Detecting the interference of waves is one of the most powerful methods in science for measuring wave phenomena, and using the waves and their interference can reveal underlying details of their sources and the materials through which they travel.

This activity quantifies an experience many students have had visiting a beach, or even playing in a sandbox. A summer afternoon walk, barefoot, across sand can burn one's feet. Often people take a few steps and then bury their feet in the cooler subsurface sand as they make their way across the beach. After sunset, the surface sand cools rapidly and buried feet are warmed by the deeper sand that has not cooled off yet. Stopping to rest on an empty fire ring, the beach walker notices how warm the concrete ring is long after the Sun has gone down.

The length of the day is something we take for granted. Yet, much can be learned about the day -- and the way the Earth moves -- from careful observations of the Sun and a more distant star, over as little as 24 hours, with a home-made viewer and a good clock.