A core idea in physical science is that matter can be subdivided into particles that are too small to see, but even then matter still exists and can be detected by other means. This idea is one of the core physical science ideas included in A Framework for K-12 Science Education, Practices, Crosscutting Concepts, and Core Ideas (see Chapter 5). The Framework states that by the end of grade 5 students should know:
Matter of any type can be subdivided into particles that are too small to see, but even then the matter still exists and can be detected by other means (e.g., by weighing or by its effects on other objects). For example, a model showing that gases are made from matter particles that are too small to see and are moving freely around in space can explain many observations including … the appearance of visible scale water droplets in condensation, fog, and, by extension, also in clouds or the contrails of a jet. … (Page 108)
As you will see below, Bonnie's students' exploration of condensation led them to infer that water can be subdivided into particles that are too small to see.
Throughout their consideration of the aquarium, students repeatedly brought up observations and ideas about condensation on a water bottle. In fact, they often seemed more interested in the water bottle than the aquarium. Among their comments, students noted that condensation formed on cold bottles but not on ones at room temperature, and that once a bottle was wiped dry, condensation would reappear almost immediately. Through their observations, questioning and reasoning students began to talk about condensation forming from water in the air:
Video 1
Examining the video. Despite the many hours of discussion about evaporation, up to this point Bonnie's students had not focused on moisture in the air. Every group of students is different. It is interesting that, for this group of students, the effort to understand condensation invoked thinking about water in the air, whereas other groups became interested in that idea in relation to evaporation, cloud formation, or rain.
In lines 16 to 17, Landon says there's always moisture in the air because water is always evaporating. In lines 29 to 30, Bonnie responds by asking why you can see moisture on the bag, but not just hanging in the middle of the room. What reasons could Bonnie have for asking this?
In lines 31 to 38 Seth responds to Bonnie. What are Seth's ideas, and what is his evidence and chain of reasoning?
The following video occurs just a few moments later:
Video 2
Examining the video. How do Seth and Ella contribute to the development of the idea of small particles as a model for water in the air? Based on the videos presented here, how would you characterize the students' development of the idea of small particles as a model for matter? What are some responsive next moves Bonnie could make?
By the end of the session above students were comfortably talking about condensation on a cold water bottle as coming from water in the air or moisture in the air. The following video shows how Bonnie opened the next science session:
Video 3
Examining the video. Bonnie opened this session by asking students to explain what was happening in the covered aquarium between the water in the bottom and the condensation at the top. In what ways is she responding to students' ideas in the previous discussion? In what ways is she facilitating the development of the idea that that water can be subdivided into particles that are too small to see? What evidence in the transcript indicates that students are continuing to develop and make sense of a small particle model?
Delving deeper. Click here to delve deeper into how the events on this page align with the new Framework and NGSS.