Another great tool is in development to help poor rural off-grid schools: The Kinkajou projector. It uses a super-bright white LED shining through microfilm, so it is low-power, robust, cheap, and can provide an entire library of course materials. And it can be powered off of a solar panel that stores up juice during the day for projecting at night. (Too bad there's no way to store daylight as light and then release it later!)
The project was originally an assignment for some classes at MIT, but the torch has been taken up by Design That Matters (which we've mentioned briefly before) and they're getting help and funding from USAID and World Education. Though its design has won many awards, it is still in development, not a full-blown product yet--they are currently testing 45 of the projectors in village schools in Mali and Bangladesh. The project's design journal (which is an impressively thorough documentation) says "the current solar panel and battery power supply developed for the World Education test is far too expensive for volume production", so they are investigating other power sources. However, they may be being overly hard on themselves, as a NewScientist article says the projector only costs $12. While still a large sum for a family in the target markets, that should be affordable by many villages.
The device is quite similar to the "leapfrog lighting" products we've described previously (they even use the same LED's by LumiLED), but the addition of microfilm to make it a teaching tool breaks new ground. A few spools of microfilm can hold an entire basic-education curriculum (obviating even the need for highly-skilled teachers), are certainly more robust and cheaper than anything electronic, and are probably cheaper and less prone to decay than books.
The projector was designed for use in adult literacy, HIV awareness, and other continuing-education classes, which are generally held in the evening because people have to work during the day. However, I suspect half the benefit of this invention is replacing books with a microfilm library, so there may be a valid role for this projector in daytime primary school classes. In these cases, no LEDs or power would be needed--you could rig up a little periscope-with-lens to capture and concentrate some sunlight from outside into the projector. The room itself would need to be somewhat dark, but not pitch dark; the better the light-concentrating lens, the more normal indoor light levels you can have.
