Reddit reviews Schaum's Outline of German Grammar, 5th Edition (Schaum's Outlines)

https://www.clozemaster.com/languages/learn-german-from-english

Any German workbook for Grammar

a B1 Book such as The Little Prince

Extra German: Cheesy sitcom aimed at high school students

That's basically what I did except for Spanish

I used to teach 1001-2001 at a major university in the US.

You're having trouble learning in the classroom? Are you spending at least three hours outside of class for every hour spent in class? That's the recommended amount of homework/ review work to do well in any college-level class.

Here are some other tips.

1. Turn on German music or German movies in the background. Netflix has a ton of German movies. You can watch recent German TV shows here: http://www.zdf.de/ZDFmediathek#/hauptnavigation/startseite A German radio station with lots of news and German/ indie music is http://dradiowissen.de/ Turn on subtitles while you watch movies on Netflix. Write down words you hear that you don't know and then look up the definitions... using a paper dictionary, not an online one. (Studies have shown that people are more likely to forget what they read on a computer screen!) When you have a few free minutes on the bus or wherever, review the words that you wrote down.
   
   No matter what you do, make a point of doing this every day. I have an Austrian friend whose mom is a moderately famous Slovakian-born author who writes in German. Her (=the Mom's) German was admittedly lousy when she moved to Austria. However, every day, she made a point of watching a cooking show she liked and learned a ton of German from that. If you hate cooking shows, don't watch them. : ) In this case, the cooking show was helpful because there are a lot of repetitive actions and very useful nouns and verbs - food words are really important! : )
   
   
2. http://www.nthuleen.com/teach.html has a lot of great exercises. I also recommend http://www.amazon.com/Schaums-Outline-German-Grammar-5th/dp/0071824707/ref=sr_1_9?ie=UTF8&qid=1412112434&sr=8-9&keywords=german+grammar It's cheaper than Hammer's and also has a whole bunch of exercises to do. I've also heard good things about http://grammatiktraining.de No, it's not the communicative method. But if you ever want to remember all of the damned articles and endings, you're just going to have to sit down and do rote exercises.
   
   
3. Ask your instructors about any language immersion/ "Sprachbad" weekends that you can participate in or any "Stammtisch" nights. If someone speaks English to you, speak back in German.
   
   
4. Make a point of doing the orientation course before your semester begins next year. They are generally really good at exactly that - helping you get oriented. (Almost all of the social groups for the semester or year were cemented within a couple of days every time I went abroad as part of an exchange, so it's helpful for meeting people, too.) There will be people from other countries who will say, "Oh, Tubajewman! You are an English native speaker! Let's speak English; I want to practice my English with a native speaker!" You will have to put your foot down and say, "Yeah, but we both came here to speak German and not English, so let's speak German!"
   
   
5. These days, most universities also have "tandem programs" or "mentoring" via the international office. Sign up to do one, both at your home university and when you are away. In the US, you'll be responsible for making a foreign student feel welcome, and in Germany, someone will help you to get acclimated and settle in. People are usually paired with someone from a country or region where they share a mutual interest. In the US, I was given German tandem partners; in Germany, my tandem partners had studied in the US. When you get together, it's a good chance to practice speaking both languages.
   
   ETA - Reddit automatically changed my numbering. The stinkers! : P

Highly recommended if you're willing to spend a few bucks (and if you're willing to put in hundreds of hours of your time this is a good investment)

http://www.amazon.com/Schaums-Outline-Grammar-Edition-Outlines/dp/0071824707

Look at the two-star and three-star reviews of "The Everything Learning German Book" on Amazon. They suggest that the book is poorly organized and that the CD isn't well integrated with the text. I'd stay away from that one, if I were you.

Whatever book you buy should depend on your language study plan. If you're going to use Duolingo as the core of your program, you can probably buy a grammar outline like Schaum's. This is what I'd recommend, personally.

On the other hand, if you really do want an integrated course, I see that Ultimate German and Complete German both got good reviews.

If you have a specific goal for the language, I might recommend something different. For example, if you are going to Germany in three months and just want "survival German" or if you're an academic and simply want to be able to read papers in German. If you have a linguistic background, I might suggest something more sophisticated than Schaum's. But from the info you gave, I think Duolingo plus Schaum's will give you the best result.

Best of luck!

Schaum's Outlines has exactly what you're looking for. They did wonders for my proficiency in the language. There's explanations of grammatical concepts (first book) or vocabulary (second book) followed by exercises, whose answers are in the back.

Viel Glück!

http://www.amazon.com/gp/aw/d/0071824707?pc_redir=1408083361&robot_redir=1

http://www.amazon.com/gp/aw/d/0071615474/ref=mp_s_a_1_6?qid=1408491041&sr=8-6&pi=SL75

Not sure if this is exactly what you want, but in my intermediate class we're using Schaum's Outline of German Grammar, it is mostly exercises, with answers in the back.