I am currently studying a language so long flights are just the perfect time to "quiz myself" in that language. Either by flash-card videos or un-subtitled dubs of a movie in that language
Which language exactly? I am currently studying kanji with anki during my commute.
I am studying mandarin, I could probably be using my time doing some writing in my commute. I use a plethora of apps / download youtube videos / rosetta stone