The devices involved are Motorola Xoom tablets—used together with a solar charging system, which Ethiopian technicians had taught adults in the village to use. Once a week, a technician visits the villages and swaps out memory cards so that researchers can study how the machines were actually used.

After several months, the kids in both villages were still heavily engaged in using and recharging the machines, and had been observed reciting the “alphabet song,” and even spelling words. One boy, exposed to literacy games with animal pictures, opened up a paint program and wrote the word “Lion.”

The experiment is being done in two isolated rural villages with about 20 first-grade-aged children each, about 50 miles from Addis Ababa. One village is called Wonchi, on the rim of a volcanic crater at 11,000 feet; the other is called Wolonchete, in the Great Rift Valley. Children there had never previously seen printed materials, road signs, or even packaging that had words on them.

The computers make use of the "Nell System", which has some interesting science fiction roots:

The interaction design of the Nell system described above is inspired by the “Young Lady’s Illustrated Primer” in the Neal Stephenson novel The Diamond Age, from whose protagonist Nell takes its name.

Nell’s design embodies four key ideas: it is a Narrative interface using Direct Interaction which Grows with, and is Personalized for, the child. Nell uses these four key concepts to build a novel learning platform which addresses several challenges we’ve encountered in earlier work.
(From Growing Up With Nell: A Narrative Interface for Literacy)

The apps running on the tablet were inspired by the software running on the primer, a runcible computer, a book-shaped computer that has paper-thin LCD displays for pages:

Nell's first experience with the Primer

The book spoke in a lovely contralto, with an accent like the very finest Vickys. The voice was like a real person's - though not like anyone Nell had ever met. It rose and fell like slow surf on a warm beach and when Nell closed her eyes, it swept her out into an ocean of feelings.

Once upon a time there was a little Princess named Nell who was imprisoned in a tall dark castle on an island in the middle of a great sea... from time to time a raven would come to visit...

"What's a raven?" Nell said.

... it turned out to be a bird. Big letters appeared beneath. "R A V E N," the book said. "Raven. Now, say it with me."

"Raven."

"Very good! Nell, you are a clever girl, and you have much talent with words. Can you spell raven?"

...After a few seconds, the first of the letters began to blink. Nell prodded it.

The letter grew until it had pushed all the other letters and pictures off the edges of the page...
(Read more from Stephenson's Diamond Age primer)

(Compare this fictional narrative with this description of an Ethiopian girl interacting with Nell.)

However, this idea has additional science-fictional antecedents. In his 1992 novel A Fire Upon the Deep, Vernor Vinge describes a specialized portable computer called a dataset that runs educational software in "kindermode":

The sounds and vids kept the monsters amused for several minutes. Eventually their random fiddlings convinced the dataset that somebody really young had opened up the box, and it shifted into kindermode. ...

"My name is--" Johanna heard a short burst of gobble with an overtone that seemed to buzz right through her head. "What is your name?" Johanna knew it was all part of the language script. There was no way the creature could understand the individual words it was saying. That "my name, your name" pair was repeated over and over again between the children in the language program.
(Read more about Vinge's dataset (Pink Oliphaunt))

You can take a look at the apps Nell's Balloons and Nell's Colors, which require modern browsers like Chrome or Firefox to run.