A search for a vocabulary book usually turns up a mix of very different kinds of books, grouped together only because they share a shelf. They don't all work the same way, so it helps to know which type you're actually looking at.
Root-based builders
These books teach word roots, mostly from Greek and Latin, on the idea that one root unlocks a whole family of words at once. Merriam-Webster's Vocabulary Builder is a book built this way, grouping words by shared roots so you learn the pattern, not just the word. This approach suits people who like spotting patterns and building from a small set of building blocks.
Drill workbooks
A workbook, like the Vocabulary Builder Workbook style of book, is closer to a course: short lessons, practice questions, and a clear sense of progress from front to back. This suits people who want structure and don't mind a bit of repetition to get there.
Word-a-day collections
These present one word per page or per day, usually with a definition, a sample sentence and sometimes its origin. Word Power Made Easy by Norman Lewis is a well-known example, built around groups of related words introduced a few at a time. It's a gentler pace than a workbook, better suited to reading a little at a time rather than sitting down to study.
Reading itself
A novel, a long-form article or nonfiction pitched slightly above your usual level teaches vocabulary differently from any of the above: you meet new words in context, surrounded by clues about what they mean, rather than in an isolated list. It's slower to build a specific set of words this way, but what you learn tends to stick because you met it while reading something you cared about.
No downloadable challenge here, but something free
If you came looking for a printable or downloadable vocabulary challenge, we don't have one to offer. What Tile Streak does have, free and online, is a word of the day and graded vocabulary word lists you can work through directly on the site, along with a vocabulary quiz to test what's sticking.
Picking one
If you like patterns, start with a root-based book. If you want structure and a sense of finishing something, a workbook suits you better. If neither appeals, our app roundup covers digital options, and how to increase your vocabulary covers habits that don't need a book at all.