It's best to have at least a basic understanding of programming before tackling the exercises on exercism.io. You also have to know how to set up your development environment, as you will be coding everything locally (versus websites that provide you an editor right in the browser).
The most recent edition of "Programming in Scala: A Comprehensive Step-by-Step Guide" was published in January, 2011. Scala is a fast evolving language, which means many of it's new features (such as Futures/Promises) are not covered in this book.
"Functional Programming in Scala" offers no shortage of exercises. Throughout the book, exercises and examples are plentiful to help the reader put what they're learning into practice for a better understanding.
Many Scala books aim to teach not just the language, but programming theory as well. "Scala for the Impatient" focuses only on teaching the syntax and features of Scala, making it a great option for experienced programmers looking to pick up the language quickly.