[1]
Purpose
To give students an opportunity to draw a model that explains what they observed in Student Experiences 1 and 2.
Description
Ask students: If you had a pair of super strong glasses [2] (stronger than the most powerful microscope), what would you see in the three graduated cylinders (filled with water, alcohol, and water and alcohol combined)? Have students draw pictures of what they would see in their science notebooks or using this task sheet [3]. [Task instructions for pilot teachers. [4]]
[5]
Questions to Ask Students
- Describe your drawing. What does each part represent?
- How does your drawing explain what is happening when alcohol and water are mixed together?
Student Thinking
Some students’ drawings will represent water and alcohol as continuous (that is, they will not draw water particles (Benson, Wittrock, & Baur, 1993; Nakhleh & Samarapungavan, 1999; Renström, Andersson, & Marton, 1990; Séré, 1986 [6]). If students draw particles, look for:
- Size and shape of particles in different states. Some students believe size and shape change as the states change (Aydeniz & Kotowski, 2012; Özmen, 2011; Özmen & Kenan, 2007; Tsai, 1999 [6]). For example, some think water particles are bigger in the vapor phase than the solid phase.
- Number of particles. Some students believe that the number of particles changes as the state changes. (Lee, Eichinger, Anderson, Berkheimer, & Blakeslee, 1993; Osborne & Cosgrove, 1983; Russell et al., 1989; Tytler, 2000 [6]). For example, some students believe particles disappear when water evaporates.
Implementation Tips
- The drawings will help the teacher understand what students think about matter at this point in the pathway and be alert for opportunities for students to challenge their thinking.
- Collect and keep the drawings, or ask students to keep the drawings, so they will be able to compare their thinking at this point with their thinking at the end of this driving question pathway.