Hueber allows you to view the first few pages of the Arbeitsbuch online for free:
Unlike many textbooks that make you buy a separate teacher’s manual, this workbook has a full Lösungsschlüssel (answer key) in the back. This is crucial for self-learners. You can do a page of Präteritum exercises and check your work immediately. menschen+a22+arbeitsbuch+pdf
When searching for and downloading PDFs of books or workbooks, it's crucial to consider the legal aspects: Hueber allows you to view the first few