{video_title}

Number disks are non-proportional units used to further develop place value understanding.  Like money, the value of the disk is determined by the value printed on it, not by its size.  Number disks are used by students through Grade 5 when modeling algorithms and as a support for mental math with very large whole numbers.  Whole number place value relationships modeled with the disks are easily generalized to decimal numbers and operations with decimals.