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Purpose
[stextbox id = “info”]To give students an opportunity to draw a model that explains the conservation of weight during phase change (that is, weight stays the same during phase change).
[/stextbox]Description
[stextbox id = “info”]Have students draw what they would see in the ice cube and liquid (contained in the plastic baggie) if they had super strong glasses [2], more powerful than the most powerful microscope.
[/stextbox]Questions to Ask Students
[stextbox id = “info”]- Describe what’s in your drawing. What does each part represent?
- How could you use what you drew to explain your prediction about the weight of the ice cube before and after melting?
- How are your drawings for the ice cube and liquid different from your first ones, if at all?
Student Thinking
[stextbox id = “info”]- Many students believe matter (in this case water) is continuous rather than made up of particles (in this case water molecules) (Benson et al., 1993; Nakhleh & Samarapungavan, 1999; Renström et al.,1990; Séré, 1986) [3]. These students are likely not to include water particles (or any other kind of particles) in their drawings.
- They may also think particles are IN substances (water particles in a body of water) (Beerenwinkel, Parchmann, & Gräsel, 2011; Lee et al., 1993; Novick & Nussbaum, 1978, 1981) [3], which should also be evident in their drawings.
- Students may think that there is NO space between particles (Benson et al., 1993; Özmen, 2011; Özmen & Kenan, 2007) [3].
- Students may not understand that the particles are constantly moving, even in ice (Herrmann-Abell & DeBoer, 2011; Lee et al., 1993) [3].