Is Yr used before words that start with vowels and is Y used before words that start with consonants?
Yes, but that isn't quite the full explanation -'r is an option as well. Look at the 'Hints and Tips' for the section 'The' to see when to use 'r, yr or y - you will need to use a web browser, as the Duo app does not show tips.
The (In Welsh):-
• If the word before (the), ends with a vowel, it has " 'r " added to the end of that word, regardless of what comes after it. So, if the word before doesn't end with a vowel, then:-
• "Y" is used before a word beginning with a consonant.
• "Yr" is used before a word beginning with a "H" or a vowel. ("W" and "Y" are also vowels in Welsh.)
Does one need to be subscribed to the duolingo in order to access course notes, hints & tips etc ? I have literally found no extra clues & have learnt so far by guess work & trial & error, & the odd comment has been helpful ...