For example, if the task at hand is to teach the children to subtract eight from 21, the instructor should group ten of the blocks together, perhaps in a tower formation, and then grouping the additional 11 blocks together in a group that is laying flat on the desk or working surface. At this stage, if the child fully understands how to count far beyond ten, they will recognize and be able to express that the tower consists of ten different blocks. The instructor would then praise this accomplishment to reinforce motivation and cooperation and then ask the child to express the amount of blocks laying on the surface. They should correctly identify that there are eleven blocks by counting them out loud one by one.
At this point, the instructor reinforces that the task is to subtract eight of these blocks from the different formations and then regroup the blocks into a different series. The instructor might remove only two blocks from the tower and then six more from those on the table to provide example. The child will recognize that the tower now contains only eight blocks and should be able to regroup the surface blocks to account for the additional six blocks needed to complete the equation of 21 – 8 = 13. When the child is given free rein to perform another subtraction task through regrouping, they should accurately recognize, as part of mastery of pre-operational and concrete operational understanding, how to regroup the different blocks to achieve a positive math outcome.
The teacher, for students in this phase, will not be dealing with egocentric behaviors marked by those found in children who are in the pre-operational stage and should expect full cooperation to the regrouping tasks. By allowing the children to choose their own ordered sets of blocks, based on the specific math task, they will begin to develop the ability to perform these calculations in their