An important concept in Regents Earth Science is that the altitude of the star Polaris above the northern horizon is approximately equal to the observer's latitude. In this case, the term altitude simply refers to the angle of something above the horizon. Traditionally, this measurement would be made with instruments called astrolabes, sextants, or even clinometers. For years, I had my science students create their own astrolabes using this template. They would then use these instruments to measure the altitude of a cardboard Polaris I hung in our school's atrium. They would measure the altitude from various locations, simulating what it would be like to measure the actual altitude from various locations in the northern hemisphere. When I got my first set of iPod Touches, I was excited at the potential uses of the built-in accelorometer for this lab. Low and behold, developers designed a variety of astrolabe apps that accomplished the same thing as the more traditional instruments. Using the iPods instead of the astrolabes made the activity more engaging and fun, and it allowed students to really undertstand the concept of altitude.

This year, I have been using iPads, and so I immediately sought out an astrolabe app that was native on the iPad. I was very excited to find SeeLevel. This app allows the user to look "through" the screen using the device's camera. A bullseye on the screen can be lined up with any object while the angle above the horizon is displayed on the top of the screen. Despite my constant fear that students would drop the iPads, the activity went well and students really grasped the concept. Check out this photo of the kids in action. By the way SeeLevel can also perform a variety of other measurement tasks, and is definitely worth checking out. It's currently available for $0.99 on the iTunes Store.

Tags: Polaris, Latitude, Altitude, Clinometer, Astrolabe, Sextant, SeeLevel, SeeLevel App