The Smelly Traveler

Purpose: Investigate to determine how a smell moves and how fast a smell travels.

Materials

• onion
• food chopper or chopping knife and cutting board
• yardstick or tape measure
• stopwatch or watch with second hand (1 per participant)

Procedure

1. Ask an adult to purchase an onion.
2. Place the onion on a cutting board or in a food chopper, that rests on a stable location such as a tabletop or kitchen counter.
3. Give each participant a watch and send a participant to a room in the house. Make sure that each room has no more than one participant! Note: Stand as far back in a room as possible and keep the room door wide open.
4. Use the yardstick to measure the distance from the onion in the kitchen to each participant (observer) in your investigation.
   • Be sure to start the measurement at the exact location of the chopping.
5. Record the distance to each observer on the data sheet provided.
6. Ask an adult to chop the onion and open the lid to the chopper.
7. Ask the participants to start the stopwatch the instant the adult begins to chop the onion.
8. Ask the participants to yell out "I smell the onion" at the instant the smell is observed. Stop the watches immediately.
9. Participants are to report the information to the recorder and wait until all others have done the same.
10. Once all have reported their time, discuss the following questions:
    • What was the farthest distance the smell traveled?
    • How fast could the smell be detected one room away?
    • How long did the smell take to reach the farthest room from the kitchen?
    • Was there a pattern to the movement of the smell through the house?
    • What does this information teach you about a smell and the distance and rate at which it travels?

Helpful Hints: As you conduct the investigation, keep in mind that windows, air conditioning, or heaters may have an effect on the outcome. Be sure to take accurate measurements!