I think most of us are already aware of the importance of regular review and try to incorporate it into our classes. In ESOL adult the challenge is the range of language systems and skills, as well as literacy and exam strategies that we need to fit into part-time learning. If there is barely enough time to cover the syllabus then reviewing is restricted because it also takes time. In the past, to review vocabulary I used a'word box' where tricky vocab was written large on cards, put in the box and retrieved at the start/end of the next class for verbal questioning e.g. - how do you pronounce it? give me a synonym? Is it formal/informal? change it to past, to a noun etc? When students felt sufficiently familiar with a word it could be discarded from the box .This was quite effective but again the reason I stopped doing it was because an extra qualification was 'shoehorned' in to our courses and most of our time and energy directed to this - good practice easily falls by the wayside in an imperfect world!