One of the most major breakthroughs in preventing the spread of illnesses and infections in hospitals was embarrassingly simple. Wash your hands. In 1846, Hungarian physician Ignaz Semmelweis discovered that hand washing played a vital role in the spread of germs, and the practice soon became mandatory in hospitals. The simple act of scrubbing hands with soap and water literally saved lives.

Getting a kid to wash their hands, however, can be an uphill battle. One teacher did a simple experiment to show her students just how important hand washing is.

"We did a science project in class this last month as flu season was starting," teacher Dayna Robertson wrote on Facebook. "We took fresh bread and touched it. We did one slice untouched. One with unwashed hands. One with hand sanitizer. One with washed hands with warm water and soap. Then we decided to rub a piece on all our classroom Chromebooks." Robertson later noted that they normally do make a point to sanitize the classroom Chromebooks, but didn't that day in the name of science.

RELATED: A 5th-grader made a discovery about stuffed animals and germs. It landed her in a medical journal.

The bread was put into plastic bags and the germs were left to fester. The bread that had been touched by unwashed hands and the bread that had touched the Chromebook had the most mold on it. The experiment proves that nothing beats soap and water. The bread that had been touched by hands washed with soap and water remained (relatively) good enough to eat.

This experiment has been done before, but Robertson expanded on it by testing the effectiveness of hand sanitizer. The bread that had been touched by hands cleaned with sanitizer also had a fair amount of mold on it, although not as much as the bread touched by unwashed hands.

"As somebody who is sick and tired of being sick and tired of being sick and tired," Robertson wrote. "Wash your hands! Remind your kids to wash their hands! And hand sanitizer is not an alternative to washing hands!! At all!" It's kind of making us retroactively gag over seeing port-a-potties with hand sanitizer set up in lieu of sinks.

The experiment was prompted by a different science lesson. "We had just finished a science lesson on how leaves break down during winter. The kids were kind of grossed out by the mold, so we decided to run our own version using germs and mold from our own environment," Robertson told Scary Mommy.

RELATED: A brutally honest kindergarten teacher shares five reasons why she quit the profession

Weirdly, the classroom experiment received some criticism. "Lots of people actually DEFENDED not washing their hands!" Robertson told Scary Mommy. "That was shocking! It really was just a simple classroom experiment to teach about mold but we have all learned more about how easily we can spread the germs we can't see."

The moral of the story is, please, please remember to always wash your hands.