Hi to all,
I accidentally discovered great ODK resources on stats4sd website by Alex Thomson and Emily Nevitt.
On each page, youtube video and slideshow are downloadable as mp4 and pptx files
Other ODK resources about xlsform and ODK(in Spanish) are also available : https://stats4sd.org/resources?query=xlsform%20odk)
A big "thank you !" for this contribution