FINDING THE SUM MORE ABSTRACTLY
A dynamic addition problem is written on the form. This time add all of the units first, making the necessary changes. Write the total for the units under the units column and go on to add all of the tens. Where did these two tens come from? Those are the result of changes you made when adding up the units. (The carried over tens are not recorded anywhere.)
After each column the child records the total. The result when completely written corresponds to what is seen on the frame.
Form 999 on the bead frame. Add one unit. The result, 1000 was obtained by making three changes.