‘Hide Particles’ viewing option to the ‘View Particles’ viewing option marks a shift
in the students’ task from one of prediction to evidence, from theory to empirical fact.
Observation: Patterns and Comparison
Finally a student, Hilary, offers the teacher the evidence that he wants.
Hilary: If we go back to the liquid
Teacher selects the Liquid to Gas screen with the ‘View Particles’ viewing option
(shown in figure 6.13)
We can see that they are moving around in the same kinda way.
Teacher: Good. They’re moving around kinda the same way and they’ve got
kinda the same arrangement.
Teacher selects the Gas to Liquid screen with the ‘View Particles’ viewing option
Points at the particles on pan lid and circles them
If we look they’re kinda the same kinda arrangement. Excellent. Well done.
Circles the particles on the saucepan lid
The student, Hilary, adopts the style and the discourse of the teacher. The teacher
facilitates the student positioning herself in this way by following her implicit
instruction to change the screen image from ‘gas to liquid’ to ‘liquid to gas’. In doing
so the teacher enables the student to take up the resource of visual comparison and
movement between the screens in the CD-ROM. The observation is focused here on
the drawing out of visual interpretations and patterns within the CD-ROM. This is a
crucial point in the lesson as the comparison between screens enables the student to
generalise the entity particle from a specific state of matter. The particle is no longer
‘a gas particle’ or ‘a liquid particle’ it is a particle that can be arranged to realise
different ‘states of matter’. The student’s comments connect with the visual icon for
the button ‘states of matter’ that started the lesson in which the image of ‘particles’
indicates the criterial aspect of ‘states of matter’.
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