Control of error
Control of error is the feature built into a Montessori material that shows the child a mistake without an adult saying anything: a cylinder with no hole left to go in, a step that breaks the line of a stair.
The clearest example is the knobbed cylinders. Ten cylinders go back into ten holes in one wooden block. A child who drops each cylinder into a hole a little too big ends with the largest one in hand and only the smallest hole empty. Montessori's verdict in 1912 was short: "The didactic material controls every error."
The adult stays out of it
Her 1914 handbook puts the control in the material itself, so the child has concrete evidence of the mistake and corrects it. No teacher points it out.
The adult still corrects something: rough or careless handling of the material. Mistakes of order are left alone, because repeating the work sharpens the child's eye until the child fixes them.
Some controls are in the wood, some are in the eye
In 1917 she called the cylinder block the most mechanical control of all. One mistake leaves a cylinder out, and the exercise can't be finished until it is corrected.
The pink tower, the brown stair and the red rods have no such check. A cube out of order still sits on the tower. The child's eye alone supplies the control, which she says makes these harder than the cylinders, and the eye they need is trained first on the cylinders. That is one reason the cylinders come before the tower in the sensorial sequence.
Read the row before you present
Every lesson on this site has a Control of error row in its table. When it names the material, show the work and step back. When it says the adult or the child's own ear, as it does for the moveable alphabet, plan to stay close for the first weeks.
Sources
Passage numbers point into the public-domain texts this site checks every citation against.
- The Montessori Method, Maria Montessori (1912), ch. XII, passage 39863:250: A child who puts each cylinder in a hole a little too big ends with the largest cylinder and only the smallest hole; the material controls every error.
- Dr. Montessori's Own Handbook, Maria Montessori (1914), Sensory Education, passages 29635:33, 29635:35, 29635:36: The control of the error lies in the material itself; the teacher corrects rough use, not errors of order; the cubes, prisms and rods have no control in the material, the eye alone supplies it, after preparation with the solid insets.
- Spontaneous Activity in Education, Maria Montessori (1917), ch. IX, passage 24727:105: The solid insets carry the most mechanical control: one mistake leaves a cylinder out and the exercise cannot be completed.
To see this at work across a whole area, the sensorial lessons list every lesson in order, with its age and materials.
Related terms: isolation of difficulty, three-period lesson, prepared environment. All eight are in the glossary.