https://www.vocabulary.com is excellent (and free).

'agog' entry:
https://www.vocabulary.com/dictionary/agog?family=Agog

Try the tab 'challenge' - it will teach you words, test you in various ways (which is part of teaching), keep track of your progress, choose words to be learned based on it. Create separate accounts for you and your child. You can specify which words to learn too. One good list is https://www.vocabulary.com/lists/52473#view=notes 'vocabulary.com top 1000 words'.

Last edited by arlen1; 06/12/13 08:46 PM.