HEALTH
Use our resources to better understand why the five-second rule is . . . misunderstood.
Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit.

Photograph by Rebecca Hale, National Geographic
Discussion Ideas
- What is the “five-second rule”?
- The five-second rule is an urban legend that contends it takes five seconds for food or utensils dropped on the floor or ground to become contaminated.
- “Scientifically speaking,” the BBC reminds us, “there is no five-second rule.” Why?
- According to the BBC, “there is not a swarm of bacteria lying on the ground, waiting to pounce on any food that comes their way. Instead, they are already everywhere, even if you have just mopped the floor . . . At any one time, there are about 9,000 different species of microscopic creatures lurking in the dust in our homes, including 7,000 different bacteria.”
- Bacteria and other microbes are not just around our houses, they’re on us. Watch this great video for an introduction to some of your biological houseguests.

Photograph by Rocky Mountain Laboratories, courtesy National Institute of Allergy and Infectious Diseases
- Where might coming into contact with microbes be very unsafe—where would you never want to obey the five-second rule? Use your common sense and the BBC article for some help.
- doctor’s office, hospital, or other health-care facility
- portable toilet
- home, office, or classroom where someone is sick
- area with poor sanitation facilities
- Where might coming into contact with microbes not be so harmful—where might you want to risk quickly rescuing dropped food? Disclaimer: All content provided in this post is for general information only. It should not be treated as a substitute for the medical advice of your own doctor or any other health-care professional!
- In many clean, dry places, contact with the microbial world can actually benefit us, because we have evolved with microbes all around us.
- One expert says “If there are microbes on that piece of food, it could [therefore] contribute to the development of the healthy immune system. I say go ahead and eat it.”
- Another expert thinks “even licking your floor or your toilet seat is unlikely to make you sick.”
- Biologists and anthropologists who study our “gut microbes” like to remind us that “You don’t build an immune system by being a germophobe.”
- In many clean, dry places, contact with the microbial world can actually benefit us, because we have evolved with microbes all around us.
TEACHERS’ TOOLKIT
BBC: What really happens to food when you drop it on the floor?
Nat Geo: Misunderstood Microbes video