Science project

Is It Safe To Eat Something Dropped On The Floor As Long As You Pick It Up Within 5-Seconds?

Research Questions:

Shoes harbor bacteria and help transfer dirt and germs from one location to another, which means we probably shouldn't eat food that's been dropped on the floor. However, people have come up with a “five-second rule,” which says that if food has been dropped on the ground for five seconds or less, it can still be consumed safely. But is this true?


  • Chunks of bread
  • Microscope
  • Well slide
  • Pen and paper for notes

Experimental Procedure:

  1. Put a piece of fresh, untouched bread under a well slide and view it under a microscope. Look for bacteria and record what you see.
  2. Drop another piece of bread on the floor for one minute. Pick it up and put it under a well slide, again for viewing under a microscope. Record the amount of bacteria that you see.
  3. Now drop a third piece of bread and leave it on the ground for 30 seconds. Once again, record the amount of bacteria.
  4. Finally, drop a piece of bread for less than 5 seconds and view it under the microscope. What do you see?
  5. Compare the four pieces of bread and how much bacteria you saw on each one.

Terms: bacteria; dirt; germ transfer; timer

References: Bacteria: Life History and Ecology; Fundamentals of Microbiology, by IE Alcamo (Jones and Bartlett, 2001)

Disclaimer and Safety Precautions provides the Science Fair Project Ideas for informational purposes only. does not make any guarantee or representation regarding the Science Fair Project Ideas and is not responsible or liable for any loss or damage, directly or indirectly, caused by your use of such information. By accessing the Science Fair Project Ideas, you waive and renounce any claims against that arise thereof. In addition, your access to's website and Science Fair Project Ideas is covered by's Privacy Policy and site Terms of Use, which include limitations on's liability.

Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.

Add to collection

Create new collection

Create new collection

New Collection


New Collection>

0 items