I'm working as an aide in an elementary school resource room and have, more or less, been charged with conveying the idea of regrouping with several special ed fifth graders. It's something they have all been exposed to before, but for one reason or another, have lost their understanding of over the summer. We've tried trading chips, using base ten blocks, drawing base-ten type diagrams, writing numbers in expanded notation (or I guess that's what it's called, where 347 is written as 300 + 40 +7?), to try to communicated both the ideas of place value and regrouping. It's been suggested by administrators that we put the "why we do it"s on the back burner and try to teach them steps they can memorize and use instead. Some of them are okay with the regrouping algorithm, but some of them don't even have that. We've been doing subtraction since August! I'm at a loss. It's my understanding that subtraction was pretty much under their belts at the end of last year, also, so I'm discouraged that it's taking so long to get a firm grasp on it again. So... does anyone have any ideas about what I can try, or what tools might help them in remembering? Are there rhymes or songs about subtraction? Or fail-proof books that veteran teachers use? I'm not new to education- I've tutored for years!- but I'm new to the special ed classroom, and to teaching (as teaching and tutoring are, in practice, very different animals). Thanks for any suggestions you all may have!