We have introduced another transferring activity this week. The children use a special spoon (picture a teeny tiny ladle) to pick up one marble and put it in the bottle. When they are done they carefully pour the marbles back into the bowl. The control of error here is the marbles make a loud clanking sound when they fall off the spoon.
Most of the materials in the practical life are self-correcting. "The control of error through the material makes a child use his reason, critical faculty, and his ever increasing capacity for drawing distinctions." Dr. Montessori
(The Discovery of the Child, 1967, p. 103).