A book that has helped me with German.
I've read many posts about what others use to help them in learning a language or languages, in tandem with Duolingo. A book I really like and have used in the past (and will again) is "German Demystified", by Ed Swick. It covers just about everything you'd like to learn and includes writing exercises and quizzes (and the answers are in the back). While teaching, it does so in a way that doesn't confuse me, and I confuse easily. I just wanted to pass along a book that I enjoy using to learn to speak German. :)
It's funny because I'm reading the same book as well :). What is even more great about it that it follows somewhat the same topics here in Duolingo at the same pace and order.
by the time I finished the first 15th lessons here on Duolingo I was able to run through the first 5 chapters in the book with little to no problems. the book is about 20 chapters, 420 pages. and it gets harder as you progress.
The book also introduces new topics, the vocab is for sure much diverse. However I don't tend to collect or write all the vocab I encounter in the book, you would get alot of lets say useless words that serve you nothing at the mean time and level. Once I'm done with say half the book I'll start from the beginning and collect more words that I left the first time.
10/10 absolutely a must have book.
I use "Intermediate German: a grammar and workbook" by Anie Miell and Heiner Schenke, it is very intuitive and direct with the grammar, and it also is for beginners (I am a beginner and haven't found any problem using it).
I recommend this website for grammar issues: http://www.germanveryeasy.com/
Is the book your talking about ("German Demystified", by Ed Swick) a workbook? One you can write in and answer questions and activities that coincide with the information taught?