Developmental Considerations in Science Education

Elementary school teachers face a unique challenge as educators. Every good teacher must cater their teaching strategy to the cognitive developmental level of his or her students. However, in the case of elementary school, teachers must do so for students that are essentially developmentally moving targets!

All educators are familiar with the work of the famous Swiss developmental biologist Jean Piaget. Let’s recall some of Piaget’s developmental stages:

  • Sensory-Motor Stage: Birth-2
  • Preoperational Stage: 2-7 (egocentric, logical/abstract thought difficult)
  • Concrete Operations Stage: 7-11 (logic develops, but thinking is limited to actual physical objects)
  • Formal Operations Stage: 11-16 (abstractions become possible)

If we plot Piaget’s pre-operational through formal operations stages against age, we get the graph shown below. In this figure, we have added a rectangular box to indicate the corresponding age-range of students in typical elementary schools. At a glance, one can see that all three Piaget developmental stages plotted here are represented in the elementary school population. Thus, depending on the age/grade level of students, teachers must deal with students of significantly different developmental and cognitive levels.

To illustrate how age and cognitive development may influence student’s comprehension of fundamental science concepts, let’s consider a study we recently conducted with students at a public elementary school in Pennsylvania. We worked with classrooms of first, third, and sixth graders, using measures to gauge their understanding of three important science concepts: time/age, ordering of objects, and conservation.

Concept of Time/Age

To examine students’ conception of time/age, we asked first, third, and sixth grade students to say whether the following statements were true or false:

  1. You will grow older, but your father will stay the same age.
  2. Your mother and your grandmother are the same age.
  3. Your grandfather was born before your father.
  4. You and your mother are the same age.
  5. If someone was born first, then they are older than you.
  6. You were born before your teacher was born.
  7. Your grandmother grows older every year.
  8. If someone is bigger than you, then that person is older than you.
  9. You grow older every year.
  10. If someone is five years older than you, they will always be five years older than you.
  11. Someone is two years older than you, but you will catch up to them and be the same age someday.

Next, we scored the results and plotted the data against grade level as shown in Time, below. As can be seen, there was a significant difference between student concepts of time/age at each grade level.


Ordering of Objects

To examine students’ conception of the ordering of objects, we asked first, third, and sixth grade students to arrange the three objects shown below according to weight. The students were permitted to handle the three objects and place them in correct sequence from lightest to heaviest. The three items are shown below in the correct orderIn general, the challenge hinged on the differentiation between the lighter rubber “moon ball” and the heavier battery, since the moon ball had an equal or greater volume than the more dense battery.

The scores of this test were then plotted against grade level and are shown in composite graph above (Ordering). As can be seen, the first and third graders had very similar results and were less successful in ordering these objects than the sixth grade students.


Piaget performed a series of landmark experiments with children centering on a concept he termed conservation. For example, when he poured liquid from a large, wide glass into a tall, narrow glass, young children consistently reported that there was more liquid in the tall, narrow glass.

We performed a modified version of Piaget’s conservation experiment as shown in the figure below. In this study, we transferred colored water from a reservoir closed with a stopcock to a glass flask. We did so in the indicated four stages, stopping at each stage and then continuing until all of the colored water was in the reservoir. This demonstration was performed slowly and in full view of the students.

Students were then given a photograph with the top four pictures of full, partially full, and empty reservoirs on it as shown above and had to match the four empty, partially full, and full flasks to the appropriate reservoirs. The important science concept at work here is the physical law of Conservation of Matter. This law states that matter cannot be created or destroyed. In this experiment, for example, any combination of reservoirs and flasks other than that shown would necessitate either the creation or destruction of matter. The results of the performance on this task are plotted against grade-level in the composite graph above (conservation).

As can be seen, there was little difference between third graders and sixth graders performance in this experiment—both performed very well. On the other hand, the first grade students performed significantly poorer on this conservation task than the third and sixth grade students. Apparently, first graders don’t have a problem with destroying or creating matter! In any case, the results of this conservation experiment would not be surprising to Piaget, as he found similar results.


Summary: Importance for Elementary Science Education

As we can clearly see in the composite graph above, very different results were obtained for different aged students when different science concepts were tested. Thus, while there was a clear difference between each grade tested in terms of Time, first and third graders performed quite differently than sixth graders in Ordering. In contrast, third and sixth grade students both performed similarly and well on the Conservation exercise, in clear contrast to the first graders.

These results tell us something very important about teaching science at the elementary school level—we must always be cognizant of the developmental level of our students. Different science concepts may represent different cognitive challenges to students of different grade levels. As important, we must remember that not all students within a single grade are at identical cognitive developmental levels (despite what Piaget may have believed). Thus, some students in a second or third grade class may have a harder time with a particular science concept than other students in their class, while having little trouble with another science concept in the very same class.

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