Discrepant Event - May the Force Be with You

Egg in Bottle Investigation

This is a an investigation into “forces” discrepant event in which students make observations of an event and then explain the science that caused the event.

This simple; however complex, investigation is a great attention getter for learning about forces and atmospheric forces.

May the Force be with You

Materials: (per group)

• One hard boiled egg with shell removed

• One clear plastic or glass bottle that has an opening narrow enough that the egg will not fit through

• One strip of paper about one inch by six inches

• One box of matches

Procedures:

1. Light the piece of paper with a match and place the paper inside the bottle
2. Place the egg in the opening on top of the bottle
3. Observe what happens

Expected Observations:

As the paper burns inside the bottle, the bottle will fill with smoke. Shortly thereafter, the students will observe the egg begin to slowly change its shape to fit through the bottle opening as it slides through the opening. Suddenly the egg will fall through the opening and land at the bottom of the bottle.

Questions to Ask Students:

• What did you observe? (Common answer is that the egg was sucked into the bottle.)

• What force or forces caused the egg to enter the bottle? (Common answers include air in the bottle forced the egg inside or gravity pulled the egg inside.)

Science Behind the Discrepant Event

The burning piece of paper heats the molecules of air in the bottle. This causes the molecules of air to move further away from each other. When the flame goes out, the molecules of air in the bottle cool down and move closer together. This is what scientists refer to as a “partial vacuum “. Normally the air outside the bottle would come rushing in to fill the partial vacuum created inside the bottle.

However, the egg is in the way! The “push” or pressure of the air molecules outside the bottle is so great that it literally pushes the egg into the bottle. Gravity causes the egg to fall to the bottom of the bottle.

Discrepant Event Resource

Teaching Science Using Discrepant Events