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Purpose
1. To confront students with a phenomenon that they need to explain—that is, how odor travels.
2. To help the teacher and students become aware of students’ thinking about the particle nature of matter.
Description
Place a liquid with a strong odor (e.g., orange slices, perfume, vinegar) in an opaque container so that students are unable to see the substance. Provide all students an opportunity to smell the container with the lid on (students should not be able to see or smell the substance with the lid on). After all students have had a chance to smell the container, place it at the front of the room and remove the lid. Ask students to raise their hands when they are able to smell the odor (Merritt & Krajcik, 2013) [2]. After all hands are raised, ask students to imagine that they are wearing super strong glasses [3] that are more powerful than the strongest microscope, allowing them to see the odor up close (Loughran, Mulhall, & Berry, 2004) [2]. Ask students to draw a picture illustrating how the odor gets from the container to their nose using this task sheet [4] (Merritt & Krajcik, 2013) [2]. [Task instructions for pilot teachers. [5]]
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Safety Tip
When deciding what substance to use, be aware of student allergies.
Questions to Ask Students
- How do you think the odor moved from the container to your nose? If students say the odor is in the air: How did it get there?
- Why couldn’t you smell the odor when the lid was on the container?
- Did everyone smell the odor at the same time? Why not?
- Describe your drawing. What does each part represent?
- How does your drawing explain how the odor got from the container to your nose?
Student Thinking
Students are likely to draw fog, clouds, lines, dots, circles, or any combination of these (Merritt, Krajcik, & Shwartz, 2008) [2]. Students may show movement in their drawing using wavy lines, or arrows, or they may not show movement at all. Some students refer to odor as “wanting” to get to the nose or to get out of the container (that is, they may give human qualities to the odor). Others will think that the nose attracts the smell, like a magnet attracts certain metals.
Implementation Tips
- A container with a wide opening will allow the odor to spread more quickly.
- In order to make sure the odor you select is strong enough that all students in the room will be able to smell it, attempt the activity in your classroom a day or two prior to enacting with your students. Stand in various locations around the room and confirm that you can smell the odor from your container in those locations.
- 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 (for example, in their science notebook), so they will be able to compare their thinking at this point with their thinking at the end of this driving question pathway.