I use this place value Smartboard lesson to model for my students how to regroup tens to ones. I pass out base ten blocks to them and a tens and ones work mat, and we work through the activity together. It sure beats hopping around from desk to desk making sure they have the right idea. I first have the students model on their work mat the number shown and then call on volunteers to regroup. Then you can slide down the blue bar to reveal the new tens and ones. Included is a free download for a tens and ones work mat.