Strategies for introducing the particle view of matters: cognitive conflicts, practical activities, multiple representations and assessment for learning (A0543)

Abstract

This presentation reports teaching strategies that aimed to introduce to Grade 7 students for their very first time the particulate nature of matter. The project was a collaboration between school teachers and university science education researchers. This presentation aims to be very focused, to the extent that it describes the teaching strategies of a 40-minute lesson that were adopted by school teachers participated in this project. The lesson was an orchestration of (a) practical work, (b) the use of cognitive conflicts, (c) the use of students’ generated multiple representations, and (d) with a strong flavour of assessment of learning (AfL). The particulate view of matter was introduced to students as a resolution to a puzzling phenomenon, namely, the volume contraction of mixing water and alcohol. Key components of the lesson were as follows: (1) Students were asked to mix 50ml of alcohol and 50ml of water, and to record the volume of the mixture. They were also asked to record the mass of the alcohol, the water and the mixture. The activity aimed to create a cognitive conflict among students, who were likely to expect a conservation of volume. Class discussion followed. It aims to solicit views from students about the reason for the volume contraction (AfL). At this point, the teacher would not offer the explanation, and left the phenomenon as a puzzle. (2) The teacher suggested that in order to solve the puzzle, the class would do another activity. This activity involved mixing 50ml of sagos (very tiny tapioca) and 50ml of soya beans. The students were expected to measure the volume of the mixture after a thorough mixing. (3) Students were asked to explain their findings, i.e., volume contraction of the mixture, by using words and diagrams (AfL by student-generated multiple representations). The teacher would then do a roundup session that examined students’ explanations. (4) Using a diagram, the teacher introduced to students how water might be like at a submicro level, i.e., it’s made of a vast number of water particles that were too small to be seen by naked eyes or any microscopes. Then, students were asked to use words to describe the spatial arrangement of water particles in the diagram. It was a means where the teacher could assess students’ interpretation of the diagram (AfL, by multiple representations). Then, the teacher introduced to students the diagram representing alcohol (with alcohol particles having a larger size than that of water particles). (5) The teacher pointed out that the volume contraction of water/alcohol mixture could be likened to that of sagos/soya beans. Students were asked to explain the volume contraction introduced in (1) by the use of both words and diagrams. This was another AfL opportunity where the teacher could be informed of students’ learning from the metaphor. The presentation will be supplemented by classroom videos. Further comments about the teaching strategies and their limitations will be made in the light of the classroom practice as demonstrated in the videos.