Scrabble makes learning fun, especially during one on one tutoring/lessons IF used sporadically and over the long term.
Scrabble can be an incredibly powerful learning tool with some caveats. Teachers must be purposeful in its use and plan for it. You cannot simply have students play scrabble without direction. For instance, I have students "prepare" to play by doing research on strategies, vocabulary (including two letter words), and mathematical calculations. I had one student keep track of letters that have been played not knowing that the app can keep track of what is left. Also, it is best to limit the time and have students earn the right to play. Again, if Scrabble is used haphazardly as a class "babysitter", it is just another game. But if you plan to use Scrabble like you would any other educational activity, you'll find that it can be incredibly effective and make learning fun.
How I Use It
I teach home school learners and tutor full time. So, I have the unique opportunity to work one on one with students. One of the teaching tools I use is Scrabble on the iPad. So, my students have to earn time playing scrabble and it only occurs the last 10 minutes of a lesson. Best of all, they LOVE to earn time playing me after sessions or at nighttime. We have turned it into math lessons by looking at the tile values and the probability of pulling certain letters. We have compared strategies and written persuasive essays about whether its better to play a smaller word with large point values or a larger word to draw more letters. Most of all, we use it as vocabulary tool. We use the "best word" function but ONLY if they look up the word that the app recommends and writes, not just a sentence, but an entire paragraph around that word. Essentially, they are buying the use of the cheat function. It's been an awesome experience for my students and has made my job that much more fun.