FOSS gamedev and creative worlds

Hi
I added the teaching mod - I can use it under my login.

If I try to use other logins, when I add an Alphabet block, it shows, but disappears almost instantly.

What have I done wrong?

http://wiki.minetest.net/Privileges
maybe you don't have sufficient privileges

Where can l find the teaching mod?

Sfan5's Teaching mod: https://github.com/sfan5/minetest-teaching

...requires the 'teacher' privelage to place blocks properly.