4A - 4B - 4C - 4D - 4E

### Module 4: How the Students See It

D. Classification Skills

In the planetarium we classify all sorts of things:
stars, planets, nebulae, star clusters, galaxies, and subclasses of these objects.

How do students perceive our descriptions of the way these objects are classified?

 Classification Skills Egocentric Level Egocentric Level (starts about age 4) Can notice similarities and differences, can only classify after much trial and error, and  cannot systematically classify a large number of objects. Concrete Level (starts about age 8 or 9) Beginning with classification by a single trait, can later recognize that objects may belong to more than one class, and can arrange objects along a continuum. Formal Level (starts about high school age) Can arrange objects in a hierarchy and then rearrange the objects in a new hierarchy.

Egocentric example:
Distinguish an asteroid or small moon from a planet by virtue of its roundness or lack thereof.

Concrete level example:
Earth is in the solar system and in the galaxy at the same time.

Formal level example:
A high school senior might well be able to understand how astronomers classify galaxies, nebulae, and clusters, and then subclassify these into various types (e.g. open or globular clusters)

The different levels of classification reasoning are demonstrated in the solutions to the following problem.

Students of various ages were given 6 pictures of galaxies and

asked to classify them any way they wished.

For each student response, what is the reasoning level that the student is using.

 1. “Basically, there are two kinds of galaxies; spirals and non-spirals. The spirals might be seen face-on or sideways, and the non-spirals might be either elliptical or irregular in shape.” 2. “The pictures in the bottom row are all spirals and the pictures in the top row are not spirals. Also, the ones here (on left) are skinny, the middle ones are egg shaped, and the ones here (on right) are rounded.” 3. “In order from nicely shaped galaxies towards more squiggly galaxies.” 4. Regarding these galaxy groupings:

 Summary of Piagetian Levels of Development Egocentric Level starts about age 4 Concrete Level starts about age 8 or 9 Formal Level starts about high school age Frames of Reference Can imagine only one’s own point of view. Can imagine another viewpoint, but only after a concrete experience. Can imagine a situation from different points of view. Scientific Explanation Skills Attributes motives and purposes to inanimate objects, or assumes all phenomena are produced by human actions for human purposes, e.g. “The sun comes up so we’ll feel warm.” More complex relationships between various elements familiar to the individual can now be used to explain phenomena. New observations can be appropriately used in revising explanations. Can extend explanations to predict new observations and objectively compare one’s own explanations with alternatives. Classification Skills Can notice similarities and differences, and can classify only after much trial and error. Can classify by a single trait, recognize that objects may belong to more than one class, and arrange objects along a continuum. Can arrange objects in a hierarchy and then rearrange the objects in a new hierarchy.

4A - 4B - 4C - 4D - 4E