Cognitive theory of Jean Piaget includes four stages of development that children move through during which the explanatory behaviors of infants transform into the abstract, logical intelligence of adulthood. There are three important specific characteristics of Piaget's theory of which the first one is being a general theory, that is, cognition's all aspects undergo a similar course of change. Another characteristic is that children move through the stages in an invariant sequence. Piaget believed that there is a same order that children follow. Third, the stages are universal. Stages in cognitive theory assume the theory to include all children everywhere (Berk, 2003). Biological concepts are used in a limited way in Piaget's theory. However, he stated the importance of genetic and environmental factors on the way that children move through the stages (Crain, 2005). He emphasized that the speed of children while passing those stages is affected by differences in genetic and environmental factors.
Jean Piaget used the term scheme while explaining human beings' organized way of making sense of experience (Mark, 1969). Traill (2008) explains that the term scheme used by Piaget is different from people's everyday usage of scheme. The term can be any pattern for exploring and learning from the environment and it has three different intellectual structures. Piaget calls first intellectual structures to emerge as behavioral schemes, ones that appear after 2 years as symbolic schemes, and structures that appear after 7 years as operational schemes (Piaget, 1972, as cited in Traill 2008). For instance, dropping scheme of an 8 month old baby and a 25 months of will not be the same, as sooner it will become more deliberate and creative. Toddlers, different from infants, begin to think before acting and Piaget identifies that transition from sensorimotor to cognitive approach to the world which depends on mental representations. (Piaget, 1926, as cited in Berk 2003) Images and concepts are the two powerful mental representations.
Especially, the shift from sensorimotor to cognitive approach is accounted for two processes; adaptation, consisting assimilation and accommodation, and organization. Interpretation of new structures into already existing schemes is called as assimilation and modification of existing schemes into adaptation of new experiences is called as accommodation. Cognitive adaptation aims to adjust to the environment and is a result of the equilibrium between assimilation and accommodation (Block, 1982). While trying to grasp an object, a baby is experiencing the assimilation process, while removing an obstacle and grasping an object, a baby now accommodates the scheme (Crain, 2005). During the organization process more complex intellectual structures are combined with existing schemes by children. For instance, after the baby experienced and covered dropping movement, then he/she will relate it with throwing movement as well as understanding the concepts of near and far (Berk, 2003).
The Sensorimotor Stage (Birth to 2 Years)
Jean Piaget observed his children during their developmental period and constructs the stages based on his observations. His books mostly involve many examples from his dialogues and interactions with his children. The sensorimotor stage consists of six substages.
That stage starts with the use of reflexes from birth to 1 month. Newborn reflexes take important place in sensorimotor stage. According to Piaget inborn reflexes are consisted from first schemes. He states that as children use inborn reflexes and experience assimilation, they desire to put them to active use (Crain, 2005).
After one month, children begin to repeat their chance behaviors and primary circular reactions period (one to four months) starts. A baby experiences the thumb sucking by bringing her hand to her mouth by a chance, when the hand falls she wants to get it back and experiences many failures until she gets it back (Crain, 2005). At that example the child organizes the hand movement and sucking which is a kind of circular reaction. Piaget also states that children at that period indicate the first efforts at imitation (Berk, 2003).
The next substage is secondary circular reactions and is observed between fourth and eighth months. Infants start to experience motor achievements that encourage them to play attention to their environment. Infants begin to get enjoyment from the response of the environment to their attempts and they repeat their movements that get reaction from their surrounding (Santrock, 2004).
Coordination of secondary schemes substage takes place during eight to twelve months. At this stage infants begin to coordinate tow or more actions to achieve simple objectives. In addition with an intentional purpose, babies try to imitate behaviors after watching a person. One may be able to observe a baby at this stage trying to stir with a spoon. In addition, a baby may begin to cry when she sees her mother wearing her coat in order to stop her mother leaving (Berk, 2003).
In substage 5, tertiary circular reactions (twelve to eighteen months), children are interested with different outcomes. Piaget had observed one of his children hitting on a table at different rates in order to listen different sounds that he creates (Crain, 2005). It should be noted that all experiences are results of children's intrinsic curiosity about the environment around them that Piaget emphasizes within his cognitive development theory.
The last substage of the sensorimotor period is named as beginnings of thought or internalization of schemes lasting from eighteen to twenty months. During that substage children have the capacity to remember the behaviors that are not present (deferred imitation). Their efforts on imitation also indicate progress and they experiment with actions inside their heads. Besides, children can be observed to engage in make-believe play during that period (Santrock, 2004).
Piaget and many researchers concluded that infants appreciate concepts of permanence objects. Up to four months, children do not make any attempt to an object leaving in front of their eyes. During secondary circular reactions stage children are more able to explore their surrounding and they have a better sense of permanence of objects. At stage four children have the ability to find the hidden objects. If an adult takes a toy behind a box, the baby will look at the behind of the box and find the toy. During the stages five and six children are able to follow displacements and follow invisible shifts (Crain, 2005).
Beginnings of Categorization:
Before the capability of mental representation children are not able to categorize objects. During the first year of their life, children experience perceptual categorization. For example they can categorize the legs of an animal. Conceptual categorization begins with the end of first year; they are now able to categorize similar characteristics and behaviors. Active categorization period starts with the beginning of the second year. It is stated that sorting objects into two classes can be observed in eighteen months babies. In the second year babies can group two different kinds of objects without grasping them (Berk, 2003).
When the observed milestones of research and the description of substages of Piaget are compared from birth to two years, both similarities and differences are seen. There are points that seem to occur earlier than Piaget accepted such as categorization, deferred imitation, and analogical problem solving. Those differences are explained differently from many researchers. Some of the surveys indicate that some children born with different intellectual capacities and some of them with a set off limits which causes those differences. The latter argue the theory of Piaget in terms of biological considerations.
The Preoperational Stage (2 to 7 Years)
Preoperational stage is lasting from two to seven ages in which the child is more capable while dealing with the environment. Although the reasoning of child is still unsystematic and illogical, that is the period that children begin to use symbols and rapidly develop representation. One of the important symbols that indicate increase during that period is language (Santrock, 2004). Piaget believed that experience of internal images occurs before labeling words and he did not take language as an important tool in cognitive development of children. Berk (2003) argues that Piaget had misadjusted the role of language in early intellectual development. She proposes that conceptual abilities of children are highly affected from the dialogues of children with adults. Moreover, there are many psychologists that believe as children develop their language ability, they begin to think more logically.
Children experience transductive reasoning during that stage which means shifting from one particular to another. Children place two unrelated situations into the same case as if they have a relationship. One of Piaget's children had concluded that she hadn't had her nap yet so it wasn't afternoon (Piaget, 1924). Piaget (1924) explains that statement as an example of transductive reasoning, because the child did not catch the understanding that afternoons include many different events and having nap is only one of them.
An important milestone of the increase in mental representation is make-believe play during preoperational stage. The differences in make-believe play between sensorimotor and preoperational stage can be clearly observed. By the middle of preoperational stage make-believe play of children indicate real life conditions. In addition, by preoperational stage children begin to engage in sociodramatic play, they coordinate variety of roles and story lines during their play.
One of the criticized points of cognitive theory of Piaget is based on the belief of Piaget that play reflects children's cognitive and social skills, however there are many recent studies indicating the contribution of play on those skills. Especially during sociodramatic play, children interact with their peers longer and they are more cooperative. Many psychologists believed the role of strengthening of make believe play on a wide range of mental abilities and logical reasoning (Berk, 2003).
Piaget stated that children look at their surrounding from their own viewpoint and they ignore perspectives of others. Three-mountains study is one of the famous observations of Piaget explaining egocentric behavior of children at preoperational stage. He had used a model of three mountains and taken a child for a walk around the model in order to give opportunity for the child to look at the model from different view. Piaget had placed the child from one point of the model and placed a toy to another place. The child had been asked what he/she saw while looking at the model and what the toy would be seen while looking at it. All the children could correctly explain what they were seeing, however children at preoperational stage gave the same answer with their own view (Crain, 2005).
Studies emphasize on the relation between egocentrism and social communication. Children at preoperational stage, according to Piaget, fail to recognize the needs of their peers during verbal interaction (Rubin, 1973). As they look only from their own view, they are able to understand view of the person interacting with them. They think that they can be seen from everywhere, everybody see and hear them. An adult may observe a child at this period telling that nobody could see him/her while closing his/her eyes with hands.
Piaget (1951) proposes that the child recognizes no limits between himself and the external world and it is expected that the child would see many nonliving and non acting things as living and conscious and he explains this phenomenon as animism. In his book "The Child's Conception of World", 1951, he identifies the reason for him to use the term "animisim". He accepts that animism was term used for primitive human beings and responds the criticisms by telling that he had used that term as a generic term and emphasizing on the different types of animism in psychological origins (Piaget, 1951).
Children at preoperational stage have a belief that objects are alive because they move and grow. For example, a child may tell that "there are not any cars on the road, because they are sleeping". Piaget described animism inside four stages. Initially children accepted useful things as living. At this first stage broken or damaged objects were not alive for them. At the second stage, moving objects, whether are moved by an external factor or by themselves, were considered as alive. In stage three, to be categorized as living, things should move by themselves. Lastly, at the fourth stage, adults know that plants and animals are living things only (Moriarty, 2005).
Going through a series of steps and after changing direction is difficult for children at preoperational stage. Another well known experiment of Piaget indicates that problem in a way that there are children shown 16 boxes, 6 of which are yellow and 10 of which are red. When children are asked whether red boxes are more or boxes, children at this stage responds as red boxes and fails to be aware of that both yellow and red boxes are boxes. In his book "The Child's Conception of World", 1951, Piaget gives examples about irreversibility. There are dialogues indicating their inability such as, asking a child about her sister, the child responds that she has a sister named A, then Piaget asks the child whether A has a sister or not, the child responds that A has not a sister. (Piaget, 1951)
Inability to Conserve:
Piaget propounds preoperational child's lack of conservation by applying experiments of liquids and number. He shows two same size glasses to the children and fulls the glasses with water. He asks children which of the water was more. All the children respond that they were equal in amount. Then he puts the water in one of the glasses into a different size glass (wider or taller) and repeats his question. Children at preoperational stage tell that they are now different. They have not the capability to perceive that certain physical features of objects remain same, even their physical appearance changes (Santrock, 2004)
Based on experiments of Piaget, at the beginning of seven children begin to give the correct answer to the conservation tests. Before that age children indicates at conservation but not totally achieve it. They give answers like one is more because it is taller and then change their answers the other one is more because it is wider.
Besides, irreversibility of the child can be concluded based on the conservation of liquid experiment. The child cannot understand the end result as a reverse of the original one.
Jean Piaget also had thought about the failures of children from the linguistic point. Terms such as "taller", "more", "wider" takes time to be understood. He suggests ways to overcome that problem and tells adults to apply experiments by using different sentences and establishing questions by using different words within a particular case (Berk, 2003).
Piaget experimented conservation of children also with using number. A row of egg cups and a bunch of eggs are given to children and they are asked to take enough eggs to fill the cups. At the first half of preoperational stage children ignored the number of eggs in the cups and they made an equal length with the rows. Children at the second half of preoperational stage made one-to-one correspondence. However, those children failed in the second question. Piaget then brought together the eggs and asked which of them was more and they could not respond that they are still same. Most of them thought that the longer was more in number. Piaget explains that phenomenon as been influenced by their sudden perceptions than by logic (Crain, 2005).
In coordinating and extending knowledge in cognitive development theory of Piaget, categorization takes an important place. Researchers state that children begin to make similar categorizations and form some categories with the age of two such as animals, plants, and vehicles (Scholnick, Nelson, Gelman, Miller, 2008). Things or objects in all of those categories have differences in perceptual characteristics, so a conflict emerges with the main idea of Piaget that children's reasoning is governed by the way they see and objects appear. By the age of three children become able to make distinctions between basic and general categories such as furniture versus tables. However, children at preoperational stage are not able to organize objects into classes and subclasses based on their basic similarities and differences (Meadows, 1986).
It is argued that Piaget was partly right and partly wrong with his conclusions of preoperational stage. Researchers give simplified tasks for children and preschoolers indicate the beginnings of logical operations, however there are important differences between their reasoning and children at school age. Difficulties were observed in conservation tests, three mountains tests and appearance-reality tests. As opposed to perceptual approaches to solve problems, children rely on increasing effective mental. In order to give an example, research indicate that children who have not the capability to use counting while comparing two groups of objects, do not also conserve number. They begin to find effective solution ways for proms with more objects when they become capable of counting. Piaget states that, as many other psychologists accept, children move through variety of stages of understating, although they do not totally handle conservation up to school years.
The Concrete Operational Stage (7 to 11 years)
The beginning of concrete operational stage is furnished by logical reasoning. That period is accepted as a major turning point in cognitive development. The time that a child begins to mentally resemble an adult starts with attaining concrete operational stage. A school-aged child's cognitive performance is more evident in terms of concrete operations. For example an eight year of child's response to conservation of liquid test is that the amount has not changed and they are still same. This explanation of the child also indicates the reversibility of the reasoning that the child has now the capability to understand that the reverse is the same with the original. Their ability to achieve conservation tasks indicate their logical thinking (Richardson, 2003).
Between ages seven and ten, children take attention on relations between a general and two specific categories within the same case. Their awareness of classification is getting developed. In middle childhood period many children are interested in collections such as coins, rocks, and stamps which show their level of classification.
Children in the concrete operational stage are fairly good at the use of inductive reasoning which involves going from a specific experience to a general principle, whereas children at this age have difficulty with using deductive reasoning. Deductive reasoning involves using a general principle to determine the outcome of a specific event.
Seriation refers to the capability to arrange objects along a quantitative dimension. Ordering sticks from different lengths is one of Piaget's tests. Children at five and six years could create series but they made many errors. However, children at concrete operation stage, by starting the shortest and putting the next, indicate a perfect arrangement with an orderly plan.
Children between ages seven to eleven have an ability called transitive inference which refers to mentally arrangement of items. Piaget had showed children three stick with different colors. Children had observed that first stick is longer than second stick and second stick is longer than third stick and they had made the inference that first stick is longer than third stick. Children at concrete operation stage mentally integrate three relations at once. On the other hand, preoperational stage children can achieve analogical reasoning by encouragement of an adult (Meadows, 1989).
The ability of understanding space is more developed in concrete operational children. School age children begin to give directions as they gain more advanced space understanding. Children at five or six years indicate difference while representing an object on a person's, in front of them, left or right. Starting from seven age children achieve mental rotations, that is, they can recognize their own frame and of a person in a different direction (Santrock, 2004).
While drawing large scale areas their performance indicate important changes representing their development of cognitive skills. In the middle period of concrete operational stage children achieve to place notes showing the location of objects in their classroom. Their capability to use a rotated map is improving and also their map drawing become more accurate.
Research indicate that concrete operational thinking has a limitation that while children are reasoning in a logical manner, they are always dealing with concrete knowledge. With abstract information, they cannot catch the achievement (Crain, 2005). When they are given ideas that do not appear in the real world they are not able to indicate the same responds with concrete ones. That can be easily observed from transitional inference that when children are shown the sticks they give the correct responds whether which one is smaller or taller than the others. However, when the questions turned to a more concrete version such as "A's hair is longer than B, B2 hair is longer than C. Who has the longest hair?", up to eleven years children cannot give the right answer (Richardson, 2003).
Jean Piaget believed the importance of rich and appropriate environment for the speed of concrete operational cognitive skills of children. Many research done in small towns or villages represent the lack of rich environment and its consequences on children. Even the easiest conservation tasks are not easily achieved until the age of eleven. On the contrary, many children living in big cities, especially Western nations, have many opportunities in terms of environment and from very young periods of childhood they meet with rich and varied materials. Hence, they easily understand the conservation tasks. The same comparison had done between children receiving a professional early childhood education and the ones that spend their early period at home or street. The conclusions indicate better results of the children continuing a preschool program (Berk, 2003).
A survey had been made between Brazilian street vendors and Brazilian economically advantaged children on informal version and Piagetian version of class inclusion test of Piaget. In the informal one, the researcher asks children for the price of two chewing gums which are different. In the Piagetian one, four units of one type (mint) chewing gum and two units of the other (strawberry) one is set aside and the researcher asks "In which one do you get more money, whether you sell me the chewing gum with mint or all the chewing gum?" The success of two groups children indicates difference that on the informal version of the conservation task street vendors performed better and on the other version economically advantaged children performed well (Ceci & Roazzi 1994, as cited in Berk 2003).
The Formal Operational Stage (11 Years and Older)
The child in sensorimotor period can do things and play with objects, the child in sensorimotor period and concrete operational period can think and make reasoning about those objects. Thinking about propositions and relations different from objects and events is another period. Now human beings are bale to make coordinations of coordinations, in other words, they can combine two different groupings of concrete operations within reversibility by reciprocity (Richardson, 2003). In formal operational stage adolescents do not require concrete things as objects of thought.
Adolescents at this stage are capable of deductive reasoning. In order to overcome a problem, they start more generally and think evaluate all possible factors and then proceed to more specific predictions.
Piaget used pendulum problem in that stage in which he had showed many strings with different lengths, objects differing in weight, and in order to hang the strings a bar to children. He asked the factors that will affect the speed with which a pendulum swings. Children in concrete operational level made an unsystematic experimentation. The influences of each variable could not be distinguished by them. Adolescents of formal operational stage separate the factors that have the possibility to affect the speed into four groups; string's length, object's weight, the level of force when pushing the object, and how high the object is raised before it is released. At the end they come up to a right conclusion that the length of the string affects the speed (Berk, 2003). They work systematically in terms of all possibilities as a scientist.
Cognitive development theory of Piaget is mostly depending on mathematical and scientific reasoning; however he has some speculations on social life of formal operational stage adolescents. Piaget thinks that children between seven and ten live in here and now, whereas at the formal operational stage they start to think about long-term periods. They handle abstract ideas such as justice and love and they start to construct theories for better living world (Inhelder & Piaget, 1955, as cited in Crain 2005).
Piaget identifies egocentrism again and believes that a new kind of egocentrism is carried by utopian during that period. Piaget takes into account and repeat the forms of egocentrism from beginning to later periods:
At the beginning, sensorimotor period, infants have no idea bout the environment around them and they are egocentric, still the objects that they cannot see have no existence on their own.
At the next level, preoperational thought, children enter a representative world in terms of language and symbols. They indicate difficulty more than their own view. After a time they become aware of other perspectives and they start to think about concrete objects.
Finally, adolescents, formal operational period, meet with a world full of problems and possibilities. Adolescents feel unlimited power in themselves for their thoughts and egocentrism reappears and they are now not able to distinguish self and others' abstract views.(Crain, 2005). Teenagers feel that they are at the centre of their environment and they assume that everyone is looking at them. They spend many hours in front of a mirror feeling anxiety for the people's criticism about them. This is called as imaginary audience. Then with having a thought that everyone is observing them, they start to feel themselves special and unique and this is named as personal fable.
Adolescents do not need to refer real-life conditions and they are capable of evaluating the logic of propositions. Previously, they were evaluating statements when they were concrete in the real world. Piaget did not give an important role for language in childhood period, but he thought that it was more significant during adolescence. So, verbal reasoning about abstract situations and events is one of the important concepts in formal operational thought. Adolescents' thoughts and opinions about abstract conditions and their capacity while expressing those views are demonstration of their propositional thought. Theory and research of Piaget have greatly changed the view at infant action and thought and provided a new way of looking at children (Fischer & Heneke, 1996).
Evaluation of Piaget's Theory
Jean Piaget has contributed to the field of child development than many other theorists, as many things he expressed were the first for his time. He was the first to tell that children were different from adults and they are curious and active learners (Berk, 2003). Piaget is the founder of discipline of cognitive development. He was interested in reasoning of children and that ensured the idea of that field would be developmental and should be different from the study of adult thinking. Piaget's considerations through the idea about active roles of children on their development can be seen as obvious recently, but it was innovative for his time (Shaffer & Kipp, 2001).
Piaget tried to explain the process development and from that part he was one of the firsts who not only described the theory. Piaget's explanations had a major impact about social and emotional developmental theories. By asking many questions about intellectual development of children and creating thousands of resource for that field, he had important contributions for the educators and researchers (Shaffer & Kipp, 2001).
Many studies criticize Piaget for underestimating mental capabilities of children due to his concern with defining the underlying cognitive structure which considered performance of children on a conservation task. Piaget is criticized as assuming that child making mistake in one problem will lack the underlying concepts he was testing. Validity of this assumption is refuted by stating that performance of a child may be influenced by many other factors instead of lack in cognitive skills (Scholnick et all, 2008).
Researchers have challenged stage theory of Piaget by asking if intellectual development is at all stagelike. It is proposed that transitions in mental gradually occur and the consistency of a performance of a child in a test would be very little. For instance, problems of concrete operations and problems of formal operations may be achieved in different orders by many children with different abilities. Many theorists believe that cognitive functions are so complex that would be evaluated within a stage manner. For instance, a nine years old child may do well on verbal reasoning tests if he likes to deal with word puzzles and play verbal games, however he may not do well in mathematical reasoning (Shaffer & Kipp, 2001).
Besides, Piaget ignores cultural differences while claiming that his stages move on the same sequence in all cultures. Children from different cultures are educated differently and a s environment has a direct interaction with cognitive development, cultural differences should be taken into account to get a valid conclusion.
Implications for Education
Piaget did influence much from Montessori and Rousseau and emphasized on the importance of active learning of children. He believed that learning is a process of active discovery and should be related with the level of the child. The role of educator at giving the child appropriate and rich environment based on child's interests and modes of learning takes significant place in terms of encouraging innate curiosity of children. An environment with rich, variety, and interesting materials will encourage children to discover and become active learners (Crain, 2005).
According to Piaget educators should not teach children in a direct way, children should be allowed to construct their own knowledge through experience. Children should be given the opportunities to make mistakes and learn through those mistakes, and look for solution ways. Piaget helps educators to be aware of that, meaningful interactions of children with environment and real activities will enable children to learn. All of those factors are the roots of constructivism which is an approach constructed by Piaget and is been still used in many educational associations (Richardson, 1998).
Moral Development Theory of Jean Piaget
Piaget asked questions for children about their marble games, presented them moral dilemmas, and investigated their understanding of justice. One of the questions he asked includes two situations; in the first, there is a boy knocking over a tray of 15 cups when coming to the dinner he was requested, in the other situation there is another boy breaking a cup when he was getting from the cupboard. Piaget asked for the naughtiest one and asked for their reason. Children's answers carried out Piaget construct the moral development theory including a premoral period and two stages (Sigelman & Rider, 2006).
Premoral Period: Children of preschool children are not aware of or indicate a little awareness of society rules. Piaget does not consider those children as moral beings.
Heteronomous Morality: Children at concrete operational stage, that is between seven to eleven, are aware of the rules and think that they are put by parents and other authorities and only they can change them.
Autonomous Morality: Final stage of moral development begins with the ages of ten or eleven. They consider rules as arrangements between human beings in order to live in peace. Those rules can be changed based on the specific situations that arise between human beings. While they are judging anything, they take attention on the intention of the individual and they mostly answer the dilemma of the boy given above as the first one was naughtier that he had misbehaved and they consider the second boy a well intended (Sigelman & Rider, 2006).
Piaget states that cognitive skills and social experiences are highly influential on the process of stages in moral development. Egocentrism is an important factor on thinking of the young child. They have not the capability to look from others' perspectives and that point is related with their view of rules. So, children at earlier ages are mostly focus on the outcomes of the situations, whereas older ones take attention on the intentions.
Moral Classrooms, Moral Children: Creating a Constructivist Atmosphere in Early Education is a book written by Rheta De Vries and Betty Zan in 1994 including a contemporary adaptation of Piaget's theory for moral development of young children (Nucci, 2008.
Avoiding expiatory sanctions/punishments
Encouraging children's ownership of logical consequences
When children suggest a consequence that is too severe, asking the wrongdoer to say how he or she feels, and support this feeling
Verbalizing the cause-effect relation when natural consequences occur
Offering opportunities for restitution
When exclusion is invoked, opening the way to reinstatement
When children exclude others, helping the excluded child find a way to reenter play and improve peer relations
Avoiding indefinite consequences are guidelines for implementing constructivist alternatives to discipline in their book. (Nucci, 2008)
Social Exchange Theory of Jean Piaget
Social exchange theory of Piaget is rooted on Durkheimian conception of social exchange, in other words, it is not based on economical model, is based on morality. Many of the social exchange theories are rooted on the individual desires to maximize his profit. Piaget thinks differently and does not believe that own interests of individuals should not based on the concept of classical capitalism or the principle of reciprocity, rather it should be based on inter-personal interactions. At that point a conclusion can be stated that his social theory is not individualistic.
Meadows, Sara. Understanding Child Development.
Florence, KY, USA: Routledge, 1986. p 69.
Tracey, Diane H. Lenses on Reading : An Introduction to Theories and Models.
New York, NY, USA: Guilford Press, 2006. p 55.
Richardson, Ken. Models of Cognitive Development.
London, GBR: Psychology Press, 1998. p 124.
Copyright ? 1998. Psychology Press. All rights reserved.
y Rheta DeVries and Betty Zan. This is an excerpt fromMoral Classrooms, Moral Children: Creating a Constructivist Atmosphere in Early Education, New York: Teachers College press, 1994. These guidelines are ones that stem from a developmental approach to early education.