Table 1 Conceptual development of PNM

Renström et al. (1990)

(1) Matter as a homogeneous substance; (2) Matter as substance units; (3) Matter as a substance unit with “small atoms”; (4) Matter as aggregates of particles; (5) Matter as particle units; (6) Matter as systems of particles

Johnson (1998)

(1) Continuous substance; (2) Particles in the continuous substance; (3) Particles are the substance, but with macroscopic character; (4) Particles are the substance, and properties of a state are collective

Liu (2001)

(1) Students perceive matter to be something unnatural; (2) Students consider matter to include solids that demonstrate natural phenomena; (3) Students may perceive matter to be something unnatural that displays physical properties; (4) Students see matter as comprised of particles having natural characteristics; (5) Students might regard matter as particles that demonstrate natural phenomena; (6) Students may recognize matter as being comprised of particles that demonstrate physical properties or as something occupying different states that demonstrate chemical properties; (7) Students appreciate that matter comprises particles responsible for chemical reactions