That's easy. Computers. Even when a computer is NOT Internet-enabled, it is still a valuable teaching tool. Software programs make it a drill and practice master, or a teaching tool with interactive simulations, or a word processing tool that encourages proofreading and editing and actually enables it, too. Presentations can still be designed on it, even without the Internet's resources. It can still present media to students, such as video on CD or DVD. It has LOTS of uses besides just the WWW.
These Web sites offer extra information on the computer as a learning ...
What technology besides the Internet is the most important learning tool, and why?