I've been reading a book in print and they have "este" (no accent) as the demonstrative adjective and "éste" (accent) as the demonstrative pronoun:
esta casa (adj.)
ésta es mi casa (pron.)
But I don't see that in this lesson. Is it out of date/RAE stuff or is it only included when ambiguous and my book is being overzealous?
Also, there was a really cool little fact in the book that said that "aquél" and "éste" are used in the same way that "former" and "latter" are in English. I'm still confused as to whether the accent is necessary or optional for pronouns, however.