How Can You Be Successful When Teaching Subtraction with Regrouping?

I just read a fabulous article from the periodical Teaching Children Mathematics (March 2011 issue) about the effectiveness of teaching subtraction with regrouping.  A group of students was given a pretest beforehand and scored about 16% proficient at subtraction with regrouping from the instruction they had received the year before.  The teacher showed students examples of the error patterns they were making.  Next, to teach students about the errors they were making, the teacher gave students magnifying glasses and investigator hats so that they could become investigators to find a particular error pattern.  Students relished the idea of finding the mistakes.  As a result, the post test revealed a dramatic–more than 60% increase in proficiency of subtraction with regrouping.  This article is not available for free online, however you can purchase it at http://www.nctm.org/eresources/toc.asp?journal_id=4&Issue_id=973 or your library may have a copy.