Warm-Bottle Balloon Inflation

Balloon inflates/deflates without blowing. Ask students to predict what will happen. Put balloon over bottle; move bottle between warm and cold water. Key idea: Warm air expands; cooler air contracts. Ask: What changed inside the bottle? Safety and cleanup: Use warm—not scalding—water. https://www.google.com/search?q=%22Warm-Bottle+Balloon+Inflation%22+science+demonstration+experiment