The Montessori Materials

Montessori materials are meticulously crafted educational tools, designed to facilitate hands-on, experiential and self-directed learning, encouraging children to engage in exploration and discovery at their own pace, the aim being to nurture intrinsic motivation, independence, and a deep engagement with learning. As such, the materials -along with a trained adult, mixed-age groups and uninterrupted blocks of time- are one of the corner-stones of the Montessori approach to child development.

A display of materials in the house where Maria Montessori was born, now The Casa Montessori Chiaravalle museum, in Ancona, Italy.

“During many years of experiment and observation, I discovered that children learn naturally through activity, and that their characters develop through freedom. But these are general principles, which require practical application, and the Montessori materials have been evolved to meet this need.”

- Montessori, Maria Montessori Speaks to Parents, p. 20.

The History and Evolution of the Montessori Materials

Montessori materials have their roots in constructivism, the theory that learning is an active process whereby children construct their understanding and knowledge of the world through prior knowledge, contextual and active-learning, social interactions and reflection. This results in knowledge that is not a copy of what the child experiences, but a reconstruction of it. The ideas at the heart of constructivism can be traced back to ancient history –“I hear and I forget. I see and I remember. I do and I understand,” is attributed to Confucius, who lived 2500 years ago- but their practical application really began to take hold in the mid 18^th century

Johann Heinrich Pestalozzi (1746–1827), a Swiss educator known as the ‘Father of Pedagogy’, was one of the first proto-constructivists. He believed that that children learn through their senses, by being active and handling objects (“head, heart, and hand”) and that they should be taught in a way that mimics how they experience the world, constructing new information upon familiar. From 1805 until 1825 he was director of a school at Yverdon (now Yverdon-les-Bains) where I took this photo in 2014.

Friedrich Froebel (1782–1852) was a German pedagogue who visited Pestalozzi’s school in Yverdon, Switzerland, where he spent two years studying and teaching. Originator of the concept of the kindergarten, Froebel believed in the efficacy of using materials (or ‘gifts’ as he referred to them) as a means for children to self-educate.

The physicians and educators Jean Itard (1775-1835), and his student Édouard Séguin (1812-1880) developed a pedagogy that focused on engaging the whole child -physically, emotionally, socially and intellectually- and grounded in the idea that education should be tailored to the individual needs of the child.

Where traditional methods of education forced children to sit immobile at rows of desks, memorizing endless streams of meaningless facts and figures, Itard and Séguin emphasized the use of hands-on materials that fully engage a child’s senses, thereby freeing them to self-educate. The didactic materials that Itard first designed for this purpose are a collection of tools and exercises intended to stimulate the senses, improve motor coordination, and foster independence:

“When he found the existing methods used to teach deaf-mutes to connect words with objects did not work with the wild boy, Itard invented a method of his own. He pasted a red circle, a blue triangle, and a black square on a board, and gave the boy three pieces of cardboard of the same size, shape, and color to place on them. He went from this to more complicated exercises and eventually to a set of cardboard letters to match with a set of metal ones. The sorting and matching activities eventually resulted in the boy’s learning to pick out the letters LAIT when he wanted milk.”

- Rita Kramer, ‘Maria Montessori: A Biography’, p. 88. (1976)

This was the intellectual tradition, and these were the thinkers who helped to clarify Montessori’s thoughts about childhood education. After graduating from the University of Rome with a medical diploma, Dr. Montessori visited the hospital where Séguin had worked and read the books that Itard and Seguin had written on how to treat special children, later translating some of them into Italian. During the same period, she was working in psychiatric clinics in Rome, studying children with learning difficulties. In 1900 she was appointed co-director of the Scuola Magistrale Ortofrenica, an institute for training teachers to work with children with learning difficulties.

“Now she would be given an opportunity to experiment with the kinds of sensory teaching materials developed by Itard and Seguin: three-dimensional shapes and letters to be felt, matched, set into holes of corresponding shapes; beads, cloths, and laces to be threaded, buttoned, and tied; a whole series of objects of differing sizes, shapes, colors, textures to be distinguished and handled so as to develop skills in both perceiving and performing. She would be able to modify these materials in her own way as she observed the reactions of the children, constantly adapting the objects to the pupils’ needs as these became apparent to her.”

- Rita Kramer, ‘Maria Montessori: A Biography’, p.116. (1976)

After the results achieved by the children in the attached classroom received widespread acclaim, she referenced the help that Itard and Seguin had provided:

“I concluded my experiments upon the deficients of Rome and taught them throughout two years. I followed Séguin’s book, and also derived much help from the remarkable experiments of Itard. Guided by the work of these two men, I had manufactured a great variety of didactic material.”

- Maria Montessori, The Montessori Method, p. 79.

This was the genesis of the Montessori materials:

“Based on the apparatus developed earlier by Itard and Seguin to teach deficient children, modified by her own observations of her pupils’ reactions, she developed a set of teaching materials which she had manufactured and which she found ”became in the hands of those who knew how to apply them, a most remarkable and efficient means, but unless rightly presented, they failed to attract the attention of the deficients.”3 It was this apparatus and this presentation which later, adapted for use with normal children, became the Montessori materials and the Montessori method.”

- Rita Kramer, ‘Maria Montessori: A Biography’, p.122. (1976) [ *3. ‘The Montessori Method’, p. 261 ]

In 1902 she again enrolled at her alma mater, studying philosophy and psychology, and spent the next five years lecturing and writing on pedagogy. In 1904 she graduated and was appointed to lecture in the Pedagogic School at the university, one of the two teacher-training colleges for women in Italy, and two years later she received the offer that was to change her life:

“It was near the end of the year 1906 […] A great opportunity came to me, for I was invited by Edoardo Talamo, the Director General of the Roman Association for Good Building, to undertake the organisation of infant schools in its model tenements. It was Signor Talamo’s happy idea to gather together in a large room all the little ones between the ages of three and seven belonging to the families living in the tenement. The play and work of these children was to be carried on under the guidance of a teacher.”

- Maria Montessori, The Montessori Method, p. 85. (1912)

Maria Montessori was 37 years of age, she’d spent a decade educating herself in pedagogy, was familiar with the educational approach of Itard and Séguin, as well as the materials they’d developed from their theoretical underpinnings, and she had amassed two years of experience in using those materials with special-needs children.

“Those two years of practice are indeed my first and only true degree in pedagogy.”

- E.M. Standing, Maria Montessori - Her Life and Work, p.11. (1957)

Writing a decade later, Montessori again acknowledged her debt to Itard and Séguin and placed her approach firmly in the constructivist tradition:

“[…] thirty years after the publication of Séguin’s second book, I took up again the ideas and, I may even say, the work of this great man, with the same freshness of spirit with which he received the inheritance of the work and ideas of his master Itard. For ten years [following her graduation from university] I not only made practical experiments according to their methods, but through reverent meditation absorbed the works of these noble and consecrated men. […] Thus, my ten years of work may in a sense be considered as a summing up of the forty years of work done by Itard and Séguin. Viewed in this light, fifty years of active work preceded and prepared for this apparently brief trial of only two years, and I feel that I am not wrong in saying that these experiments represent the successive work of three physicians […] from Itard to me.”

Maria Montessori, The Montessori Method. (1912)

On 6 January 1907 the first Montessori school opened at Via dei Marsi, 58, in San Lorenzo, a slum neighbourhood close by Roma Termini, the main train station in the city. Montessori appointed Candida Nuccitelli -the building porter’s daughter- as the teacher (the first Montessori guide) and entrusted her with a simple responsibility:

In brief, the teacher’s principle duty in the school may be described as follows: She should explain the use of the material. She is the main connecting link between the material […] and the child.

– Maria Montessori, The Discovery of the Child, p. 151.

For 10 hours a day, while Ms. Nuccitelli took care of the children, Montessori sat and observed:

“I have been observing the child at work […] and have provided for him in the school a new world for his activity. In his school environment he finds objects which he can handle easily, small chairs and tables which he can manage himself, materials that satisfy his inner urge to work and teach him through his own initiative. ”

- Maria Montessori, Maria Montessori Speaks to Parents, p. 18. [2017]

She sits at her desk, watching the children, recording their actions and reactions, then acts upon her observations, adapting some materials, discarding others, endlessly refining and experimenting:

“The reactions of children to various objects, the way in which, and the frequency with which they used them, and the advantages which they derived from them, all gradually built-up reliable criteria for the elimination, modification, and acceptance of apparatus to be used in our schools. Everything about these various objects – colour, size, shape and so forth– were all determined by experience.”

- Maria Montessori, The Discovery of the Child, p. 101.

Purpose of the Materials

The principal aim of the Montessori materials is to attract the child and stimulate them into activity, because the child has the means to self-educate through deep and repeated engagement with the materials. Designed to be used after a short introduction, the materials thereby support the child in their striving for independence and act as a springboard to investigation and discovery.

“One day the teacher came a bit late to school after having forgotten to lock the cupboard. She found that the children had opened to door. Many of them were standing about it, while others were removing objects and carrying them away. I interpreted the incident as a sign that the children now knew the objects so well that they could make their own choice, and this proved to be the case. This began a new and interesting activity for the children. From this time on we made use of low cupboards so that the children could take from them the material that corresponded to their own inner needs. The principle of free choice was thus added…The free choices made by the children enabled us to observe their psychic needs and tendencies. One of the first interesting discoveries was that the children did not choose all the various objects provided for them but only certain ones. They almost always went to choose the same things, and some with an obvious preference. Other objects were neglected and became covered with dust. I would show them all to the children and had the teacher distribute them and explain their use, but the children would not take some of them up again of their own accord. I then came to realize that everything about a child should not only be in order, but that it should be proportioned to the child’s use, and that interest and concentration arise specifically from the elimination of what is confusing and superfluous.”

- Maria Montessori, The Secret of Childhood, p. 121.

Characteristics of the Materials

Characteristics of the Materials 1 – ‘Materialized Abstractions’.

Children, especially from ages 3 to 6, are concrete learners, their minds not yet ready to grasp purely abstract ideas through words or symbols alone, so the materials are concrete objects that represent an abstract rule or principle, making a complex, intangible concept visible, touchable, and understandable for a child.

“They will be able to learn for themselves something which we could not transmit by using words alone. We give an abstraction. They learn to understand this abstract concept by using the material. We call this mechanism materialized abstraction”.

- Maria Montessori, The 1946 London lectures, p. 70. [2013]

Characteristics of the Materials 2 – Appealing, child-sized and accessible.

The didactic material must be always beautiful, shining and in good repair, with nothing missing, so that it looks new to the child, and is complete and ready for use.

– Maria Montessori, Education for a New World, p. 68.

The teacher must make sure that every object used by the children has a place of its own that is easily accessible to them.

- Maria Montessori, Some Words of Advice to Teachers, AMI Communications, p. 4, 14 (1995).

The materials must be inviting and beautiful (many are made from natural materials) so they attract the children to touch and hold them. They must be of such a size that the children can handle and manipulate them, easily accessible so they can choose them independent of the adult, and in good condition:

“There should be nothing out of his reach. It is of course absolutely different from the view which states that everything should be hung so high up that it is out of the reach of the child so that only the teacher can reach it. In putting up clothes-pegs we must put them at such a height that the child himself can hang up or take down his own clothes. The same observation applies to the hanging of the pictures at such a height that the child can look at them, just as in our own rooms we hang our pictures at the right height for looking at them. As you know in our own homes we may have wall decorations above the level of the eye but pictures will always be hung at a more comfortable and lower level. We are not always accustomed in our own houses to look at paintings on the ceilings and yet for children we are accustomed to hanging the pictures so high that they cannot look at them without stretching their necks. They should be hung so low that the child can with his own hands take them down from the wall.”

– Maria Montessori, Some Words of Advice to Teachers, AMI Communications, p. 4, 14 (1995).

In the majority of the Montessori schools I’ve visited, the lids are on the boxes so the beautiful materials are hidden from the child’s view. This has always puzzled me, because it doesn’t matter how appealing the materials are if the children can’t see them.

When I’ve asked why they aren’t opened, the standard response is “to keep the dust out”, an odd justification in a room full of children who take great pleasure in dusting and cleaning.

– Maria Montessori, The Call of Education, Volume 11, No. IV, December 1925.

When I’ve asked why they aren’t opened, the standard response is “to keep the dust out”, an odd justification in a room full of children who take great pleasure in dusting and cleaning.

Characteristics of the Materials 3 – Real, utilitarian, whole and complete.

The materials must serve a purpose, but they also must be real to the child i.e., natural to their environment and culturally appropriate, e.g., transferring objects with chopsticks is commonly seen on the Practical Life shelves in many Asian countries, but might look out of place in European schools. The materials also must be whole, so that all of the individual parts are available and functional (i.e., each Cylinder Block must contain 10 cylinders), and complete so that if part of a set, the entire set must be available (i.e., all four Cylinder Blocks must be on the shelf).

“For the things we have to learn before we can do them, we learn by doing them.”

- Aristotle (384 - 322 BCE)

Characteristics of the Materials 4 – Promote experiential learning and movement.

Inviting kinesthetic engagement and encouraging active, hands-on learning is an essential aspect of the materials. A child chooses a piece of material and in the course of carrying, pouring, stacking, tying, opening and closing it they refine their sense and self-educate.

The objects in our system are […] a help to the child himself, he chooses what he wants for his own use, and works with it according to his own needs, tendencies and special interests. In this way, the objects become a means of growth.

- Maria Montessori, The Discovery of the Child, p. 150.

This process could easily lead to disorder, but the Cycle of Activity brings structure to the child’s activities, whilst simultaneously facilitating their independence. There are three stages to the cycle:

Choose a material.
Manipulate it.
Return it to the shelf.

In a Montessori environment there is often a low hum of activity, with a constant flow of children moving about the room. Some children will be deciding which material to choose (sometimes with help from the guide), others might be engaging with a material (either on a table or a mat), and some will be returning a material to the place on the shelf from whence they took it.

“The child who is handling specially designed materials at school, the child at home who is allowed to dress himself, help lay the table, in fact carry on the hundred and one activities that interest him and harm nobody, is in reality busily at work on his development – and the method of his learning is through movement.”

- Maria Montessori, Maria Montessori Speaks to Parents, p. 34. [2017]

In this photo the children are using Action Cards, a reading activity that requires them to act out various verbs: hop, sit, hum, or -in this instance- run. —————->

Characteristics of the Materials 5 – Multi-Sensory.

Sensory-based education has a long history is the western philosophical tradition.

‘Nihil est in intellectu quod non sit prius in sensu’ is a Latin phrase that translates to,

‘There is nothing in the intellect that didn´t first pass through the senses’.

This is the Peripatetic axiom and is a guiding principle of empiricism. Thomas Aquinas, an Italian theologian, adopted this principle from the Peripatetic school of Greek philosophy, and other philosophers who accepted the principle in some form include Locke, Berkeley, and Hume. Itard and Séguin belong in this tradition, as does Maria Montessori. The axiom suggests that sensory input is the foundation of human experience and is why Montessori materials utilise a range of senses, a multi-sensory approach which helps to make abstract properties concrete.

When a child carries the Red Rods to a mat, they feel the weight and see the length of the rod. When they pour beans, they engage their senses of touch and sight but also hearing, for the sound when spilled beans hit a tabletop provides an extra clue that further assists them. By seeing, touching, hearing, smelling and tasting, the children refine their senses, while learning about colour, texture, shape, size, dimension and volume, and when they’ve mastered a piece of material and want to increase the degree of difficulty, they can reduce the senses available to them, perhaps by wearing a blindfold.

Characteristics of the Materials 6 – Sequenced and ordered.

Order is very important to children, and the layout and use of the materials support this need. To begin with, they are grouped in separate and distinct areas of the curriculum -Sensorial, Language, etc.- so the child knows where to find each material when they need it, and where to return it when they’re finished.

A child is constantly inspecting his surroundings; and when a chair is out of place, making the room look disorderly, we can be certain that it will be the smallest children who will notice it. Before a child reaches the age of three, the highest form of work and the most ennobling that engages him is that of arranging furniture and putting things in order, and it is also the one that calls for the greatest activity.

- Maria Montessori, The Discovery of the Child, p. 84.

The materials are arranged on the shelves in a predictable and logical sequence, and this also supports the child’s need for order: in Group 2 of Mathematics, for example, Decimal Beads (concrete quantities) come before Decimal Cards (abstract symbols), and Decimal Operations (using concrete quantities) precede the Stamp Game (using abstract symbols), for the same reason. To the right are the shelves I prepared in my class in Taipei, demonstrating this order.

Order and sequence are also inherent in the way the children use the materials, whether cubes (Pink Tower), prisms (Brown Stairs), batons (Red Rods), or anything else: with the cubes they construct a tower, with the prisms they build a stair, and the rods have to be laid out from longest to shortest. Because of this logical and consistent order, the children develop an understanding of the sequence and hierarchy of the materials, and it is common to observe pairs of them at a shelf or cabinet, comparing where they have reached in the curriculum.

Finally, this awareness of the order and organization of the materials on the shelves inevitably leads to a more abstract order in the way children process information: order in the environment helps to inculcate order in the mind.

Characteristics of the Materials 7 – Isolate Concepts

The Montessori materials are designed to isolate one specific skill or concept. The Colour Tablets, for example, are all the same size and shape, differing only in their colour. By isolating this concept, we support the child in their focus and engagement with it, facilitating deeper understanding.

“Any object that we wish to use for the education of the senses must necessarily present many different qualities such as weight, texture, colour, form, size, and so forth. How are we to isolate from many qualities one single one so that attention may be focused on it? This is done by a series and its gradations; the objects are identical among themselves with exception of the variable quality which they possess”.

- Maria Montessori, The Discovery of the Child, p. 103.

Characteristics of the Materials 8 – Self-Correcting.

A key characteristic of the materials is that many of them exhibit an inbuilt control of error, which allows children to identify and correct their own mistakes.

[…] the control of error through the materials makes the child use his reason, critical faculty, and his ever increasing capacity for drawing distinctions. In this way a child’s mind is conditioned to correct his errors even when these are not that apparent to the sense.

- Maria Montessori, The Discovery of the Child, p. 257.

When using Tray 1 of The Geometry Cabinet, if a child places a triangle in the wrong inset, the materials provide immediate feedback. This control of error allows the child to identify and learn from their mistakes, without adult intervention, fostering a sense of autonomy and facilitating the development of confidence and problem-solving skills.

To make the process one of self-education, it is not enough that the stimulus [the material] should call forth activity, it must also direct it. The child should not only persist for a long time in an exercise; he must persist without making mistakes. All the physical or intrinsic qualities of the objects should be determined, not only by the immediate reaction of attention they provoke in the child, but also by their possession of this fundamental characteristic, the control of error, that is to say the power of evoking the effective collaboration of the highest activities (comparison, judgement).

- Maria Montessori, The Secret of Childhood, P. 61.

Of course, if the child had the right guide, they’d be less likely to make an error…

Characteristics of the Materials 9 – Embody the Spiral Curriculum

The ‘Spiral Curriculum’ is a term coined by the educational psychologist Jerome Bruner in 1960, but with its roots in a tradition stretching back to Piaget and Vygotsky. By revisiting and exploring the same materials over time, building upon prior experience, and with each encounter increasing in complexity and depth, the child deepens and solidifies their knowledge and understanding. Bruner suggested that his was a “bold hypothesis”, to which Mario Montessori responded,

“the hypothesis was bold when my mother started experimenting with it sixty years before”.

The Montessori materials become progressively more complex, moving from concrete to abstract. The first presentation in the mathematics curriculum is the Number Rods, 10 wooden rods identical to the Red Rods in dimension, the difference being that successive rods are red and blue in alternate decimetres, the number of sections representing the number of rods. This is a very concrete representation of the tactile difference between different numbers.

The second presentation is Sandpaper Numerals, introduced once the child has become aware of the difference in size between the rods. They are a set of 10 boards, identical in shape and size, with each of the roman numerals from 0 to 9 outlined in sandpaper and are an abstract representation of numbers.

Even before they receive these first Mathematics presentation, the child has been exposed to mathematical concepts. The Pink Tower is aimed at helping the child develop visual discrimination of differences in three dimensions, but a 3-year-old stacking cubes is also indirectly preparing for algebraic thinking.

1. Pink Tower – aged 3

Child builds cubes from largest to smallest.
Develops visual discrimination of dimension.
Experiences the cube physically.

2. Binomial Cube – aged 4

Introduces algebraic relationships visually.
Represents the formula (a + b)³

3. Trinomial Cube – aged 4 1/2

Represents the formula (a + b + c)³

4. Elementary Montessori algebra work – aged – 6 to 7

Children later solve algebraic expressions.

5. Cube roots and polynomial expansions – aged 9 to 10

The physical cube experience supports abstract reasoning.

Another example of this is the Baric Tablets: in the 3-6 level the child uses them to refine their discrimination of weight, and when they move to the 6-12 environments, they can weigh the tablets and use them for Mathematics, etc, and a third is the way the Decanomial Square prepares the child for later work with the Decimal Beads.

Categories / Types of Materials

Montessori materials are categorized into five areas of the curriculum, each focusing on the academic skills they support, and based on the developmental needs of the child:

Click on the links for more information on each of these categories.

Extra Materials

Along with the standard AMI-approved materials, there are a whole range of supplementary materials available, and deciding whether these should have a place on the shelves of an authentic Montessori environment has become something of a hot topic.

Dr. Angeline Lillard has published a number of papers that address the issue of supplemental materials, and in an essay on the Montessori Society AMI (UK) website she discussed some of her findings:

‘As Montessori has evolved, we might say two courses have been taken. One course has been to keep very much to Dr. Montessori’s sets of materials [at each classroom level], with few changes; for lack of a better word I will call this the Traditional approach. The second approach, which I will call the Modified Montessori approach, has been to adopt modifications in a democratic fashion, with each teacher trainer and teacher making decisions about new materials to add to the set [or in cases what to take out]. Some of the added materials are readily available commercially and are not special to Montessori [puzzles]; others are presented at and sold at Montessori teacher conferences or are in Montessori catalogues. The result after some fifty years of this is a wealth of alternative materials in many Montessori classrooms, materials in whose creation Dr. Montessori did not have a hand or mind.’

While I’m in complete agreement that diluting the materials is widespread and generally unwise (the number of environments I’ve visited with collections of dolls, play-kitchens and a box of Lego in the corner is too depressing to admit), I also feel that there are gaps in the curriculum, a curriculum that, like the bible, hasn’t been updated in a few years.

In the Language area, for example, once a child learns the Sandpaper Letters, the next presentation is the Moveable Alphabet, when they ‘write’ by combining the individual letters to create words. It’s a bit of a leap, which the AMI training fills the gap with the suggestion that the guide ‘familiarise the child with the letters by introducing them, perhaps organising or dusting them’. Indeed. But might it not be more useful to add some materials designed to reinforce the sandpaper letters?

Materials such as Matching Letters and First Sounds are an excellent way to improve vocabulary whilst reinforcing the shapes and sounds of the letters, which can be played using the Sandpaper Letters or the letters from the Moveable Alphabet, or both. Or perhaps writing activities which provide invaluable opportunities for the child to practice copying or tracing the shapes of the letters, either on paper, using the easel, in sand, on another child’s back, or in the air?

Lynne Lawrence discusses some of these and some other supplementary activities in her book*, ‘Montessori Read & Write: A Parents’ Guide To Literacy For Children’, an excellent resource for parents looking for a detailed introduction to the theory and practice of how to teach reading and writing in a Montessori way.

*Trigger warning: not all of the materials she uses are AMI-approved.

The ‘Pink, Blue, and Green’ series might be considered one of those supplementary materials, despite Maria Montessori herself playing a key role in their development: learning to read wasn’t particularly challenging for Italian children because Italian is a phonetic language, with each letter in a word pronounced, and with consistency of pronunciation across the alphabet (i.e., no phonemes). English is not as simple, so Montessori asked Margaret Homfray (who studied under her in London in 1929) to develop a reading scheme for English. The ‘Pink, Blue, and Green’ is the result.

Nevertheless, the PBG series aren’t on the shelves in AMI-accredited schools, which is a little puzzling considering the 22-year collaboration that Ms. Homfray had with Montessori, particularly in light of the fact that Montessori had so much faith in her mastery of the Montessori pedagogy that she permitted Ms. Homfray to issue Montessori Diplomas. I mean, if we can’t trust her, who can we trust?

Role of the Adult

With regards to the materials, the adult has a number of responsibilities.

“In the school also the first care of the teacher should be this: order and care of the material so that it be always beautiful, shining and in repair and nothing missing, so that everything looks new to the children and is complete and ready for use at any time.”

- Maria Montessori, The Absorbent Mind, p.397. (2014)

Our next role is to present the material to the child in the right place, in the right way, and at the right time so as to stoke the fire of the child’s interest. Following on from this, the guide must create both motive and opportunity for the child to use the materials; he does this by ensuring that the child has freedom to choose his activity, and that the environment is calm, so that he can practice without interruption. Next, the guide must ensure that the materials are treated with reverence while they are being used, and when the child is finished that they are returned to the correct place on the shelf. And all the time, the guide must practice with the materials:

“To become acquainted with the material, a teacher should not just look at it, study it in a book, or learn its use through the explanations of another. Rather, she must exercise herself with it for a long time, trying in this way to evaluate through her own experience the difficulties of, or the interests inherent in, each piece of material that can be given to a child, trying to interpret, although imperfectly, the impressions which a child himself can get from it. moreover, if a teacher has enough patience to repeat an exercise as often as a child, she can measure in herself the energy and endurance possessed by a child of a determined age. For this final purpose, the teacher can grade the materials and thus judge the capacity of a child for a certain kind of activity at a given stage of his development.”