Strengthening a different skill?
I was just about to strengthen some of my Dutch skills when something really strange happened.
I had the "colours" and "numbers" lessons which would have needed strengthening so I made an attempt on strengthening the "colours" skill. I've lost all my hearts but strengthened the "colour"-skill again.
However, after finishing the lesson with keeping all 3 hearts, Duo said that I've, instead of the "colour"-skill, strengthened the "numbers"-skill, which I haven't even touched today.
Is this supposed to be this way?
Skill strength is based on the strength of the words taught in that skill. Therefore it is very possible that practicing one skill can strengthen another skill. Additionally, turning the skill you're practicing to gold isn't always guaranteed because, while you're always strengthening the skill, it may not always move you from one tick of strength to another in a single session.