I-learn-and-play-Inkscape is a project mainly written in ..., it's free.
Inkscape plugins for easy authoring of elearning
I Learn and Play for Inkscape Inkscape extensions for e-learning authoring
HOW TO USE
For each extension you would like to use in Inkscape, move the corresponding files to Inkscape's extension directory.
E.g. using Ubuntu, the reveal-by-mouseover extension can be enabled in Inkscape for all system users by moving the .inx and .xsl files in the extensions/reveal-by-mouseover directory to /usr/share/inkscape/extensions (use sudo to copy them as you need to be root). You don't need to copy the examples folder and/or the README file.
REVEAL BY MOUSEOVER
This extension makes it easy to generate pictures that have hidden descriptions and/or graphics that appear when you move the mouse pointer over them if you view the svg in a modern browser.
It adds the required javascript to hidden objects when you save the file as type "SVG iLearnAndPlay: reveal hidden groups (*.svg)". Any svg object (or group) that is set to hidden in Inkscape (checking "Hide" in the Object Properties dialog) will be "discoverable" in the output picture.