I’ve been mulling over in my mind features that could make up a “one ebook per child” type of reader. Not looking into the distant future— 5 to 10 years down the road, and something that could be built for a low price (sub-$100, preferably sub-$50) at that time using entirely plausible technologies. It would have to be sturdy, survive shocks, and spills. It would have a vast library of books built into it, and be able to be charged in areas without regular access to electricity.
I’m thinking, it would need flexible polymer eink touchscreen display (not so that you can actually bend the unit, but so that it can survive drops and bumps in ways that glass can’t) and a polymer battery (same reason.) There could possibly be some membrane buttons for alternate input, or it may be touchscreen only. The back of the unit would be covered with flexible thin-film solar panels for recharging the unit in the sunlight.
The whole unit would need to be sealed in a watertight casing to survive spills, rain, drops in puddles, etc. Which would, of course, rule out USB ports, AC plugs, and headphone jacks. So for recharging (other than the necessarily slow solar panels), it would use an inductive charger. Data transfers to and from a computer (and possibly another ebook reader) would be via Wireless USB (480 Mbit/s.) Wireless headphones could be used via Blootooth or possibly also by Wireless USB. Longer range (but lower bandwidth) connectivity would be via Wi-Fi. Each radio frequency technology included would be able to be switched off to maximize battery life.
Memory would be vastly larger than what is installed today—already there are 64 GB USB flash drives, and the first 128 GB ones are starting to appear. It would not be at all unreasonable to put 128 GB of memory on the reader. It should come preloaded with as many public domain books as can be fit into memory while allowing for plenty of room for personal documents and purchased books. Maybe around a hundred thousand books-- drawn from Gutenberg, Google, and the Internet Archives-- would be a good round number. It also would have a portable subset of Wikipedia and possibly Wiktionary. Of course, books and resources could be added or subtracted depending on the target language of the end users.
Here’s a video of a (very basic) mockup: