If you don't have one of OLPC's XO laptops, you can run the same software on any computer from a USB disk. Follow online directions to install Sugar on a Stick.
If you want to use the laptops to make new lesson ideas, to code, or for humanitarian work, you can get a few from the Contributors Program.
Measure Kasiisi - specially reprogrammed to teach the sensors listed above. Displays realtime values, graphs, and longterm collected data.
Offline Map - an internet-optional mapping platform available for five countries. Map points, roads, and buildings; write descriptions with your photos and Wikipedia articles; explore other cities. Online Version
SocialCalc - a spreadsheet and charts program which can be shared between multiple laptops. Now available in Mongolian.
Get Books and Media - eBook search application, now with audio/video media links. Designed to work with older OLPCs and the school server.
Browse for internet access, Write for making reports, and other standard activities