Argh! Now I know the reason for those annoying reminders
I took a couple of days off from my beginner German. Now I don't know half of what I did a couple of days ago. Big mistake!
Since Duolingo isn't an intense course, it's actually a program that is better off being used every day, for about fifteen minutes or more. Of course, there will be times when you can't get online at all, but when that comes you should still practice your German. Say some phrases in your head, try spelling some words, so on so forth, just to keep the German fresh in your mind. If you feel behind, practice your weakest words or go back to the lessons that may have lost bars.
Spelling can be extremely confusing, no matter the language. I think German words are, for the most part, easier to spell than English ones. What I struggle with is remember the article that comes with the noun. When you practice spelling, add the article (like you did with die Entschuldigung), this way you'll remember it easier. Keep up the good work! (: