Hand-washing. It’s an obvious answer when it comes to preventing the spread of germs.

But by and large, most people don’t do it correctly.

The amount of time you should wash your hands might surprise you.

Doctors said you need to lather for at least 30 seconds, working between the fingers and around the nail beds too.

The old "splash and dash" just doesn’t cut it -- and adults’ bad habits are often passed on to children.

It’s in this way doctors said child illness is preventable. Hand-washing with soap and water is the number one way to keep kids from getting sick.

KVUE’s Cori Coffin met with a class at Esquelita Del Alma to test how well they wash their hands.

Using a glow gel to represent the “germs,” the children spread the neon substance on their hands until it disappeared. They then washed their hands.

Results revealed a 50 to 70 percent cleanliness rate depending on the child.

The children who used soap, washed the longest and were most diligent with scrubbing found the most success removing the “germs.”

They learned just how difficult it is to properly clean hands and actually remove germs. Watch the video above to hear directly from the children about their experience.

Doctors tout hand-washing not just as a way to prevent illness, but also as a way to fight antibiotic-resistant bacteria. Dr. Goddy Corpuz with Baylor Scott & White said soap and water are still the best defense against bacteria that has mutated over time to be immune to antibiotics.