This product has been extremely useful for my students when introducing the algorithm, or step-by-step process, of double digit subtraction. Before introducing this lesson, I had my students take a pre-assessment on double digit subtraction with and without regrouping. About 89% of my students were unfamiliar with regrouping. This information helped me build a lesson that would help explain, for some, this complicated process. I could have easily just taught them the subtraction rhyme "More on the floor, go next door and get 10 more! etc., etc.," but I wanted my students to have a visual understanding of why we need to regroup when there is "more on the floor". I blew these place value mats up (as seen in the pictures) and had the students build and record their equation. So many "Aha!" moments. I used this hands-on lesson for about two weeks before giving my students worksheets with equations. At the end of our Unit, all of my students fully grasped double digit subtraction involving regrouping. I hope you enjoy using this product with your students!