The following web site is designed to teach ESL/EFL students useful vocabulary and grammar skills through several CALL activities like multiple-choice quizzes, fill in the blanks tests, matching exercises and crossword puzzles. The activities are sorted into six levels from easy to difficult. There is also an additional section in this website that includes bilingual vocabulary quizzes covering several languages.
I really think that this is a very useful website for learning and reinforcing vocabulary learned especially due to the variety of topics covered in this site. ESL/EFL students can learn vocabulary about several topics that are categorized under nouns, verbs, adjectives, opposites, idioms, phrasal verbs, homonyms, abbreviations, slangs and many more. I truly like the homonyms’ section as it can improve both students’ vocabulary and spelling skills.
I personally would use the exercises of this website as post-task activities for my students to help them practice and reinforce vocabulary learned.
Here is a link of my vocabulary CALL website: http://a4esl.org/