Students observe the addition of unidentified “mystery matter” (baking soda and vinegar) in a container. A balloon is stretched across the neck of the container and students observe what occurs. Students then create their initial model explaining their thinking about what is happening that allows the balloon to inflate. The teacher observes students’ models, listens to students talk while they work, and raises questions about what was observed, assessing current knowledge, including misconceptions through notebook observations, descriptions and wonderings.
The second lesson of nine in a unit investigating matter and its properties, “Inflate the Balloon” provides an example of phenomenon driven instruction. Students are introduced to scientific concepts through the use of an anchoring phenomenon.