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Lecture 11: Locations and Maps

Thu. Oct 6, 2011


  • Sorry, but I'm still grading HW4s. If you want to revise your HW5 after receiving your HW4 feedback, that's fine.
  • If you got a low score on HW4 -- don't worry. It only counts for 5% of your grade. Later projects will be weighed more heavily.
  • HW6 will not be posted until after Fall Break. It will involve designing and programming your own location-aware app. You will work with a partner on this project.  Start looking for partners and brainstorming about app ideas!


In today's lecture we'll play with locations and maps, both on the web and in App Inventor.

Latitude and Longitude

Latitude and longitude specify points on the earth's surface. 

There are many web-based apps for finding latitude and longitude, such as this one.  Use it to find the latitude and longitude of (1) Wellesley College and (2) your home.

The Google maps permalink feature can be used to find the latitude and longitude of a location.  For instance, go to maps.google.com and search for Wellesley College Science Center.  Then click on the link icon in the upper right corner to get a permalink address like the following:


Can you find the latitude and longitude hidden in the permalink?

You can also use Google maps to search for latitudes and longitudes. I was born at the coordinates 40.714444,-74.355319. Enter this in a Google maps search to determine where I was born.  What hospital was I born at?  In what city?

Using URLs to query Google Maps

In class we'll see how to use URLs to query Google Maps.

URL querying and GPS in App Inventor

Upload LocationTester.zip.  This app shows (1) how to use the ActivityStarter to perform queries on Google maps and (2) how to use the GPS LocationSensor to determine the location of the phone.

Lyng Turbak,
Oct 6, 2011, 10:10 AM