Topic: Pupils explain "particle phenomena"

In line with constructivist learning theories, the students' prior knowledge must be activated and connected in order for learning to be successful. To introduce the particle concept, associations can be made with familiar macroscopic processes, such as granular structures and the separation process of sieving: depending on the size of the grains, smaller components fall through the holes of a sieve, while larger components are held back. This principle is transferred to the particle level in the "molecular sieving" experiment. In this experiment, various dye solutions are "sieved" using a selectively permeable membrane (preserving film). Depending on the size of the dye molecules, they can penetrate the preserving film or are retained. In a classroom study, the use of the experiment was tested in two seventh and two eighth grade classes at a secondary school (N = 108). Questionnaires and supplementary semi-standardised guided interviews were used to get to the bottom of the following questions:

1. Are pupils in initial chemistry lessons able to develop a particle concept independently with the help of the "molecular sieve" or does this experiment, in contrast to other experiments, make it easier for pupils to be introduced to the concept of particles?
   
   
2. Can pupils also transfer the particle concept introduced in this way to other chemical-physical phenomena?
   
   
3. How stable is the particle concept introduced in this way?

The classroom study shows that pupils are interested in the "molecular sieving" experiment despite the - for us! - analogy to the macroscopically known sieve. In a second step, in order to find out more about how the pupils arrive at these ideas, the investigations into "molecular sieving" are extended by an interview study: in these interviews, pupils explain various experiments and everyday phenomena and explain their solutions. The selected experiments (molecular sieving, dissolution processes when making coffee and the volume contraction of water and alcohol) can be interpreted with the help of a particle concept, but do not have to be. Pupils from both Year 6 and GK 13 chemistry were interviewed (N = 18). The former had not yet received an introduction to the particle concept in class, while the latter should already have a stable particle concept. The aim is to gain further insights into influences on explanatory patterns in relation to "particle phenomena".

Supervising lecturers: Prof. Dr Ilka Parchmann, Prof. Dr Marco Oetken

Wilms et al (2004). Molecular sieving: With preserving film into the discontinuum. Chemkon 11(3), 127-130.

Wilms et al. (2005). The dependence of gas solubility on temperature - an experiment with effervescent tablets. Chemkon 12(1), 27.

Wilms et al. (2005). Why doesn't Mr Gummi Bear get wet under a diving bell and why does a candle go out under a glass? - How primary school pupils become researchers in science lessons. In: Hellmich, F. (ed.). Teaching and learning after IGLU. Primary school teaching today. Oldenburg: BIS, p. 191 - 205.