i was thinking about if we should have the challenges just for whistles or for any instrumnent or if we should have one for whistles and one for ...
and i still dont know whats my opinion 😉

anyway, i met someone in a german forum, who has made a nice little easy beginner tutorial for a classical guitar tune
the good thing is, it comes with tabs and notation and it comes with nearly no language needed (just some few written words in german and english) .... so everybody who play guitar could give it a chance
its a nice training skill anyway, isnt it?

have a look

and here are tabs and notation if someone wants to learn it - i do