As it it, the Tambayayong eLib Box is released as a stand-alone deployment. No need for any upgrade with the OS. (The contents could be changed to suit the needs of partner schools.)

However, in certain cases (say, changing board to Raspberry Pi 3 Beta Plus) where a later system is needed, one may upgrade the OS. As of this writing, Raspbian “Jessie” (version 8) is used as default version of the operating system. Check if there's enough space on your microSD card. Also confirm version with

less /etc/os-release

To upgrade to the later version (“Stretch” as of this writing), connect the box to the internet via RJ-45 jack, and do

sudo apt-get update
sudo apt-get -y dist-upgrade

To ensure you have everything of the upgrade version, do

sudo apt-get update
sudo apt-get upgrade

Packages have to be upgraded as well, and they may have to be “forced”

sudo rpi-update

Edit

/etc/apt/sources.list
/etc/apt/sources.list.d/raspi.list

to ensure “stretch” is indicated. For instance,

deb http://archive.raspberrypi.org/debian stretch main ui

You may have to remove the changelog

sudo apt-get remove apt-listchanges

for faster upgrade.

Repeat the update/upgrade routine. Once done, clean up:

sudo apt-get autoremove -y
sudo apt-get autoclean

Then reboot.