"I sang a lot yesterday."
Time to bid farewell, Duolingo! I'm not learning pronunciation, but just picking shapes that I recognise; and I'm struggling with the grammar, for nothing is explained. I'm sure I would have learned far more, had I spent these hours with my head in a textbook. Time is precious. Adieu.
It's all about repetition. Reading, re-reading, and constructing sentences using your own deductive abilities really does have an impact on your learning and retention. Sometimes you do have to search elsewhere for how to pronounce certain words for which only kanji are provided, but take lots of notes while you study and eventually it'll all stick. Duolingo could do more, yes, but I'm finding that by the time I've reached level 5 in any given lesson, I really have pretty much mastered it. Just keep plugging away, my man.
I'm on mobile so I can't type in answers but am instead using word blocks. I was under the impression that よく meant frequently (how often an action is done) and たくさん meant "much" or "many", in reference to the quantity of an object. Yet here we are only given たくさん as an option. Can anybody explain why よく isn't being used here?
this is not necessarily unnatural if you want to emphasize both "私" and "昨日". (She may not have sang, but I. or I did not sing the day before yesterday, but yesterday, for example.)
I think these also should be accepted.
かった is used as part of the negative past conjugation of adjectives, so that might be where you've seen it. Here's a resource where you can learn more about the conjugation of adjectives http://www.guidetojapanese.org/learn/grammar/adjectives