Section 003 Unit 020 Duolingo Music Sheets

 Lengthen the half note by one beat

S003U020L003 Danny Boy-1

From Wikipedia:

"Danny Boy" is a song with lyrics written by English lawyer Frederic Weatherly in 1910, and set to the traditional Irish melody of "Londonderry Air" in 1913.

S003U020L007 Greensleeves-1

From Wikipedia:

Greensleeves" is a traditional English folk song. A broadside ballad by the name "A Newe Northen Dittye of ye Ladye Greene Sleves" was registered by Richard Jones at the London Stationers' Company in September 1580,^[1][2] and the tune is found in several late 16th-century and early 17th-century sources.

S003U020L010 Let's Build Something-1