Speak N Spell is an application that puts your spelling skills to the test. The program features a long list of English words, allows you to import your own lists with terms, lets you choose between five difficulty levels, and provides you with support for text-to-speech feature.
Its main window is simple and intuitive, so anyone can easily handle it. After you select the preferred difficulty level, click the New Word button and start typing the term you heard in your speakers or headphones. If you don't understand the pronounced word, you can always click the Say It Again button or skip to the next term.
In addition, the utility lets you use three hotkeys for immediately speaking the new term again, changing and showing the current word (the hotkey information is available in the Shortcuts panel from the app's main menu).
Another important advantage is the fact that you can import and export word lists. These files need to have the TXT extension.
In conclusion, I think it's worth installing this program on your Mac if you wish to put your spelling skills to the test. The app is suitable for users of all ages, comes with a built-in help guide, and is free.