What happens to the water?
Plan Investigation 6
Evaporation happens before our very eyes - the fog on the bathroom mirror clears, our clothing dries, the puddle on the sidewalk shrinks. What happened to the water? And how does evaporation happen anyway? What makes it possible?
There are some connections between evaporation and the salt that students dissolved in the previous investigation. In both processes, matter separates itself into particles that are too small to see. Also, in both processes, weight can be used to track the presence (or absence) of these particles.
Formative Assessment
What do your students’ think happens to water drops when they disappear from the outside of a cup?
Available online at inquiryproject.terc.edu
What do your students’ think happens to water drops when they disappear from the outside of a cup?
Look for evidence of students’ ideas in their annotated drawings on the notebook page What happens to drops of water?
As you interpret annotated drawings, try to gain insight into each student’s idea about evaporation.
Typically students this age may think that water that evaporates (disappears)
- has dried up and is nothing — it doesn’t exist
- has soaked into the surface material, e.g., plastic or paper towel
- has gone into the air and will become a cloud
- has transformed into drops too small to see that are part of air
Students who use the term “evaporation” may hold different ideas about what the word means.
Next steps (in feedback or discussion) might be to ask students to clarify anything you don’t fully understand, to provide more details or elaborate explanations, to explain what “evaporation” means without using the term.
Students will not arrive at definitive answers about the evaporation process today, but after they observe the evaporation of water from a paper towel and from the surface of a plastic cup, they start to propose explanations based on their observations, prior experiences, and reasoning.
By the end of this investigation students will have formulated their initial ideas through an annotated drawing about what happens to water when it evaporates.
Learning Goals
- To express initial ideas about the process of evaporation
| Sequence of experiences | ||
|---|---|---|
| 1. Ask the question | All Class | 10 Mins |
| 2. Explore | Individual | 10 Mins |
| 3. Make annotated drawing | Individual | 15 Mins |
| 4. Make meaning | All Class | 10 Mins |
Materials and Preparation
Preparation:
- Read Annotated Drawings (See Resource Quick Links). Create an Annotated Drawings poster. Save poster for reuse in later investigations.
For the class:
- Post the investigation question in a place where all students can see it.
- 1 spray mister filled with water
- 1 paper towel
For each group:
- 1 12oz cup approximately 1/4 full of water
- 1 6in strip of masking tape
- 4 1cc droppers (1cc small syringe)
- 4 paper towels
- 4 magnifiers
- 4 12oz clear plastic cups
