Baking-Soda Balloon Inflation
Three related teacher demonstrations: Baking-Soda Balloon Inflation, Yeast Balloon Inflation, Spool Rolls Toward the Pull.
Teaching & key ideas
1. Baking-Soda Balloon Inflation
Materials: Bottle; vinegar; baking soda; balloon
What you do: Combine reactants so produced gas fills balloon.
What students see: Balloon inflates without anyone blowing.
Question: What new thing is filling the balloon?
2. Yeast Balloon Inflation
Materials: Bottle; warm water; yeast; sugar; balloon; prestarted sample
What you do: Show fresh setup and a prepared older one.
What students see: Balloon slowly inflates.
Question: Is the yeast alive? What clue do we see?
3. Spool Rolls Toward the Pull
Materials: Thread spool or yo-yo; string
What you do: Pull string at different angles.
What students see: The spool may roll toward your hand or away depending on angle.
Question: Why can pulling right make it roll left—or right?
Lesson flow
Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share.
Guiding questions:
Question: What new thing is filling the balloon?
Question: Is the yeast alive? What clue do we see?
Question: Why can pulling right make it roll left—or right?