Conservation (Piaget’s Psychology): Definition and Examples

Conservation (Piaget’s Psychology): Definition and ExamplesReviewed by Chris Drew (PhD)

This article was peer-reviewed and edited by Chris Drew (PhD). The review process on Helpful Professor involves having a PhD level expert fact check, edit, and contribute to articles. Reviewers ensure all content reflects expert academic consensus and is backed up with reference to academic studies. Dr. Drew has published over 20 academic articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education and holds a PhD in Education from ACU.

Piaget’s concept of conservation refers to the child’s understanding that the properties of objects, such as quantity, volume, or mass, remain the same even when their appearance changes, so long as no additional objects are added or removed.

For example, people who have mastered the skill of conservation will recognize that pouring a liter of water from a thin glass to a wide glass does not change the amount of water we have.

But children who haven’t mastered conservation may feel like there is now less water in the wide glass because the water doesn’t go as high up the glass:

a tall glass and a wide glass with equal amounts of water in each
In this image, the volume of water in both glasses is the same. A child who lacks conservation skills will think the tall, thin glass has more water in it.

Conservation: Age and Stage of Development

Piaget believed that children develop an understanding of conservation in the concrete operational stage of development (ages 7-11 years old) of his theory of child development.

The concrete operational stage (ages 7-11 years old) is the third stage in Piaget’s stages of cognitive development. The stage is characterized by increasingly advanced reasoning and problem-solving skills.

Thinking becomes better organized and more methodical. Children are able to think logically regarding certain types of problems as they apply to physical objects, and representing those objects mentally becomes much easier.

The child is no longer limited to making judgments solely based on the perceptual properties of stimuli, but can instead use logic and perform purely mental operations to make inferences.

Children in the concrete operational stage also begin to overcome the limitations of egocentrism. The ability to look at a situation from the point of view of others, which is the foundation for social skills and emotional intelligence.

However, children still struggle with abstract reasoning.

Conservation is connected to the development of other cognitive abilities in the concrete operational stage, such as reversibility, centration, and transitivity:

  • Reversibility is when the child can mentally reverse the sequence of steps they have just observed. So, they can pass a test of conservation because they can mentally reverse the change that happened to the object.
  • Centration refers to the fact that younger children can only focus on one aspect of a situation at a time. Usually, the most salient feature of that situation will be their focus.
  • Transivitiy (aka transitive inference)refers to the ability to infer the relationship between two items based on their relationships with a third item (see: examples of transitive inference).

So, as children develop the ability to perform mental reversibility and overcome centration, they will understand conservation.

The concrete operational stage serves as a transition between the preoperational and formal operational stages.

Piaget’s 7 Conservation Tasks

There are 7 main tasks that have been developed to assess a child’s understanding of different types of conservation.

Among these tasks, some children may develop an understanding of conservation before the age of 7 years old, and some not until later.

1. Conservation of Number

Take 10 small round objects, like plastic chips, and place them in two identical rows of 5 on the table in front of the child. 

As you run your finger along each row ask:

“Does this row have more, does this row have more, or are they both the same?”

It’s okay if the child counts each row.Then, spread the chips of one row out a bit. Ask the child again:

“Does this row have more, does this row have more, or are they both the same?”   

If the child has mastered conservation of number, then they will say that the rows are equal. If not, then they will point to the elongated row and say it has more.  

2. Conservation of Length

Place two chopsticks, or two straws,  next to each other in parallel with approximately 3-4 inches in between.

While you point to each one ask:

“Is this one longer, is this one longer, or are they both the same?”

The child should answer by saying they are both the same. Next, slide one to the left and ask the same question again:

“Is this one longer, is this one longer, or are they both the same?”

If the child has mastered the conservation of length, then they will say they both are the same. If not, they will point to one and say it is longer.

3. Conservation of Liquid

For this test, you will need: two clear glasses that are exactly the same shape, preferably short and fat, one tall and thin clear glass, and one pitcher of a colored liquid (Kool-Aid or orange juice will do fine).

While the child is watching, slowly fill one of the short glasses half way. Then, as you fill the other short glass, ask the child to tell you when to stop when it is the same as the first glass.

Make sure you have filled the two glasses equally full. As you point to each glass ask:

“Does this glass have more, does this glass have more, or are they both the same?”

It may help to slide the two glasses next to each other.

Next, put the tall, narrow glass on the table. Instruct the child to watch as you pour the contents of one of the short glasses into the taller one (slowly).

Now point to each glass as you ask:

“Does this glass have more, does this glass have more, or are they both the same?”

If the child has mastered the conservation of liquid, then they will say the glasses are the same. If not, they will say the taller glass has more.

4. Conservation of Mass

Make two balls of playdough that are exactly the same size. As you point to each one ask:

“Does this ball have more clay, does this one have more, or are they both the same?”

The child should say they are both the same. However, some kids are very observant and they may say one has more if the shapes aren’t exactly equal.

Next, using the palm of your hand and while the child is watching, smash one of the balls flat.

As you point to each one ask:

“Does this one have more clay, does this one have more clay, or are they both the same?”

If the child has mastered the conservation of mass, then they will say they are both the same.

If not, then you will get a variety of answers. So, ask the child to explain their reasoning. It can reveal some very interesting ways the child has reasoned the concept of mass.

5. Conservation of Area

Get a piece of green construction paper and cut it into 12 equal-sized squares. Next, find a photo of a cow online and print two copies.

Arrange 6 squares into the pattern of a rectangle (two rows of 3). Place one photo of the cow below it. Repeat with the other squares and cow photo.

Explain that the squares are grass for the cows to eat. Point to each cow and ask:

“Does this cow have more grass to eat, does this cow have more grass to eat, or do they both have the amount of grass to eat?”

The child should answer that they are both the same.

Next, spread the squares of one rectangle out a bit. Then ask again as you point to each cow:

“Does this cow have more grass to eat, does this cow have more grass to eat, or do they both have the amount of grass to eat?”

This test will produce a wide range of answers and explanations. If the child has mastered the concept of area, then they will say each cow has the same amount of grass to eat.

6. Conservation of Weight

Use a balance scale that will be able to hold a small ball of playdough on each end.

Place each ball on the scale to show that they are the same weight. Ask the child which one weighs more:

“Is this heavier, is this heavier, or are they the same?”

The child should answer that they are the same.

Next, flatten one ball out.

Before placing each mass of playdough back on the scale, repeat the question from above:

“Is this heavier, is this heavier, or are they the same?”

If the child has mastered the conservation of weight, then they will say that they will both weigh the same.

7. Conservation of Volume

Fill two equal-sized clear glasses with the same amount of liquid (colored liquid is best).

Place two equal-sized balls of playdough on the table and ask:

“…when I put each ball into each glass, will the water rise the same amount, or will one rise more than the other?”

If the child wants to pick up each ball they can, but don’t let them alter the shape.

Then, place each ball in each glass slowly and mark the water level with a marker.

Take one ball out and flatten it on the table.

Now ask:

“…when I put this in the water, will it rise the same as the other glass, go higher, or go lower?”

If the child has not yet mastered the conservation of volume, then they will probably say that the water will not rise as much.

Criticisms of Conservation Tasks

Several criticisms of Piaget’s conservation tasks center on the methodology.

For instance, in the conservation of number task, the standard testing procedure involves asking the child the target question twice, before and after one row has been elongated.

According to Ross and Blank (1974),

“…when the child has just declared the rows equal (or un-equal), he interprets the request for a second judgment as a signal to change his response” (p. 500).

The child feels that there must be something wrong with their original response because they are being asked the same question again.

In addition, McGarrigle and Donaldson (1974) identified aspects of the experimenter’s behavior that can alter the child’s responses.

Griffiths et al. (1967) point out that children have difficulty accurately understanding the meaning of some of the key words used during testing, such as “more,” “same,” and “less.”

Conclusion

There are numerous ways of assessing a child’s understanding of conservation. The procedure involves an experimenter displaying at least two objects and asking the child a question regarding relative length, weight, or mass.

The objects are altered in some manner, followed by a second questioning regarding length, weight, or mass.

When asked the second question, after one of the objects has been transformed in some manner, if the child understands conservation, they will say that the amount of that object has not changed.

Children that have not reached this cognitive milestone will be influenced by the visual features of the transformed object, which will lead them to answer incorrectly.

Although the tasks have been widely used, there may be some methodological issues that make the results less conclusive than previously considered.

At the very least however, asking the child follow-up questions regarding their reasoning can still reveal valuable insights into their thought processes.

References

Griffiths, J. A., Shantz, C. A., & Sigel, I. E. (1967). A methodological problem in conservation studies: The use of relational terms. Child Development, 38(3), 841-848.

McGarrigle, J., & Donaldson, M. (1974). Conservation accidents. Cognition, 3(4), 341–350.

Piaget, J. (1952). The child’s conception of number. London: Routledge & Kegan Paul Ltd.

Piaget, J. (1956; 1965). The origins of intelligence in children. International Universities Press Inc. New York.

Piaget, J. (1959). The Language and thought of the child: Selected works vol. 5. Routledge, London.

Piaget, J. (1964).  Part I: Cognitive development in children: Piaget development and learning. Journal of Research in Science Teaching, 2, 176-186. https://doi.org/doi:10.1002/tea.3660020306

Rose, S.A., & Blank, M. (1974). The potency of context in children’s cognition: An illustration through conservation. Child Development, 45(2), 499–502.

Watanabe, N. (2017). Acquiring Piaget’s conservation concept of numbers, lengths, and liquids as ordinary play. Journal of Educational and Developmental Psychology, 7(1). 210-217. https://doi.org/10.5539/jedp.v7n1p210

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Dr. Cornell has worked in education for more than 20 years. His work has involved designing teacher certification for Trinity College in London and in-service training for state governments in the United States. He has trained kindergarten teachers in 8 countries and helped businessmen and women open baby centers and kindergartens in 3 countries.

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This article was peer-reviewed and edited by Chris Drew (PhD). The review process on Helpful Professor involves having a PhD level expert fact check, edit, and contribute to articles. Reviewers ensure all content reflects expert academic consensus and is backed up with reference to academic studies. Dr. Drew has published over 20 academic articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education and holds a PhD in Education from ACU.

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