What is the answer key PDF?

A separate PDF with every answer, to give away from your website, your newsletter or a QR code in the book, while the book itself stays black and white. Click "Export", then "Answer key PDF, to give away". Choose "One a page, with its key in color" or "Four a page, fewer pages", write an optional note for its first page (up to 1,200 characters, for example "Thank you for coloring! More books at yourwebsite.com") and click Export. You get US Letter and A4 files in the book's "Answer key" folder. It does not need "Answers at the back".