Well, in light of all the dumb decisions duolingo is making right now, here's a few free/accessible resources for learning Yiddish:
Ultimate Yiddish Resources Masterpost
Yiddish/Ladino Queer Vocab Glossary
And some free PDFs:
Basic Yiddish: A Grammar and Workbook, by Rebecca Margolis
A Manual and Grammar of the Yiddish Language, by J. Mazin
Colloquial Yiddish: The Complete Course for Beginners, by Lily Kahn
Idisch y Latinoamerica, by Eliahu Toker
English-Yiddish Dictionary, by Alexander Harkevy
Cursive Alef Beys Writing Practice, YIVO standard, from YBC
Digital Yiddish Library, over 12k titles for free, from YBC















