Lexxica’s Word Engine is built on research done by Charles Browne and others. He has been into Showa to speak to teachers and students about learning vocabulary. The main idea is that most books in high school teach the wrong words, words that are of very low frequency (they aren’t used much).
Here at the Word Engine, you can get your vocabulary checked in a few minutes and then study words that are most necessary to understand most reading passages. Thre are 3 or 4 vocabulary activities you can do, and the program remembers which ones you know or don’t know. You can even do some activities with your cell phone.