CTS Guide: Particulate Nature of Matter, pp 162-163- Section IV Research Summaries
Nature and Behavior of Particles
Students of all ages show a wide range of beliefs about the nature and behavior of particles. For example, they attribute macroscopic properties to particles; do not accept the idea there is empty space between particles; and have difficulty accepting the intrinsic motion of solids, liquids, and gases (AAAS 2009).
Middle school and high school students are deeply committed to a theory of continuous matter. Although some students may think that substances can be divided up into small particles, they do not recognize the particles as building blocks, but as formed of basically continuous substances under certain conditions. Students of all ages show a wide range of beliefs about the nature and behavior of particles, including a lack of appreciation of the very small size of particles (AAAS 2009).
Students do not develop particle ideas equally across all three states. Water and gases seemed to be easier substances for students to make the shift from continuous to particulate or molecular views (Nakhleh, Samarapungavan, and Saglam 2005).
Children’s naive view of particulate matter is based on a “seeing is believing” principle in which they tend to use sensory reasoning. Being able to accommodate a scientific particle model involves overcoming cognitive difficulties of both a conceptual and perceptive nature (Kind 2004).
Although some students can depict the orderly arrangement of atoms or molecules in a solid, they have difficulty recognizing the vibration of the particles (Driver et al. 1994).
An older study analyzed about 600 student drawings of the inside of a sugar crystal. The students were ages 8, 10, 12, 15, and
17. Their ideas ranged from a continuous view of matter in which the space was completely filled with non-particulate solid matter to a “continuous bits” view in which there were particles with some type of matter between the particles. The proportion of the latter view increased with age, although 20% of the students still had a non-particulate continuous view by age 17. Also as age increased, random distribution was replaced by a more ordered distribution and shapes were more uniform (Driver et al. 1994).
Particle Model
Students at all grade levels frequently do not believe in the notion that there is empty space between the particles of matter. They often hold on strongly to the presupposition that all empty spaces are filled with air (Talanquer 2009).
Students of all ages find the idea of empty space with nothing to fill it difficult to imagine and tend to intuitively “fill” it with something when asked to draw a particle model. Since students depend on sensory information such as vision and touch to develop their initial view of matter, it is not surprising that they have difficulty accepting a model proposing there is “nothing” in the spaces between particles (Kind 2004).
Researchers have associated the students’ misunderstanding of the particulate nature of matter with misrepresentation of the model in some textbooks (Harrison and Treagust 2002).
In a study by Benson, Wittrock, and Bauer (1993), elementary through college age students were asked to imagine they had magic magnifying glasses that would let them see the particles of air in a sealed flask. They drew their mental models. Students with a continuous view of matter shaded in the flask or drew continuous straight or wavy lines throughout the flask. Students with a particulate view drew dots or circles, some spread out, others packed tightly. The tightly packed drawings indicated a lack of understanding of the amount of empty space between molecules. The study also showed that 30% of college students’ drawings of air showed particles in a highly packed and orderly arrangement.