It rejected "Well, I learned it from the master", suggesting "Well I learned from the master" instead, even though it's other translation using expert instead of master has the extraneous "it".
The best change to have an alternative solution excepted is to report it. The duolingo team will most likely not see your comment here.
"Nun" means both "well" and "now"? When can we use it as "well" or "now"? Someone?
"Jetzt" means "right now". "Nun" means "now" in a weaker sense. It is also a modal particle. Those little words are common in German and very hard to translate. They don't add much to the objective content, but rather something about the attitude of the speaker towards the content.
Here, someone tried to explain "nun". He also addresses uses as in the sentence above.
There is no 'es' in the example sentence, so why is the official translation 'Well, I learned it from the master' and not 'Well, I learned from the master'? Should it not be Nun, Ich habe es vom Meister gelernt'?
"Well, I learnt from the master." should be the direct translation. Maybe this is not idiomatic?
Why did they not use "Experte"? To my knowledge, "Meister" has never before been translated as "expert." And of course there is no direct object in this sentence so where does "it" come from?