Simple experiment shows children why it’s vital to wash hands

An American teacher’s classroom experiment last autumn has gone viral. Why? Because it highlights why handwashing is so vital.

It’s not a new idea. In fact, the experiment is one you can replicate at home, and involve your own children in a memorable way to make invisible germs become a presence on our hands that they can see for themselves.

Dayna Robertson, from Discovery Elementary School in Idaho Falls, together with Jaralee Metcalf, a behavioural specialist, got their class involved in the simple experiment and our photo guide here is thanks to them.

First, get a loaf of plain white sliced bread and then take four slices from the loaf at the same point in time. Without touching the first slice with anyone’s bare hands, put it into a sandwich bag and seal it immediately.

That’s your control sample.

Next, get your child(ren) to pick up one slice each and slide it gently across their unwashed hand. Then get them to each put their own slice into a sandwich bag before it touches any other surface; so only they have touched it. Next, seal the bags and mark the bag ‘dirty hands’.

Now it’s time to get out some hand sanitizer, wipe everyone’s hands, and then repeat the exercise with a fresh slice from the loaf.

Then have everyone wash their hands with soapy water and get the slice of bread to slide over their hand. Once the slice is inside the bag mark it ‘soap’. Then take a final slice and hold it against the top of a laptop computer, or another surface that is touched by many people and rarely washed or wiped clean.

Finally, simply sit the sealed bags on a shelf or sill for a few weeks – one month was the school’s time limit, but it might not take nearly as long for your sample.

Dayna/Jaralee’s results

(All photographs - Jaralee Annice Metcalf)

The children will see that the slice touched only after the children had washed their hands with soap and water is the only slice close in appearance to the untouched slice.

The rest, even the one touched after using hand sanitizer, show a greater or lesser growth of mould, which is the direct result of microbes transferred to the bread from the children’s hands. (A word of caution here: don’t take any of the slices out of their protective bags for inspection at any point in time! Just inspect the bread through the bag and then dispose of all the bags with the slices still sealed inside in the bin.)

Clearly, unclean surfaces harbour more microbes, but more powerfully for the children perhaps, the reduction shown by washing hands with soap is clearly visible.

It’s vitally important to wash hands before (and after) handling any foods having participated in the experiment. That’s equally true after going to the toilet, blowing your nose, coughing into your hand or whenever your hands are visibly dirty. By itself, hand sanitizers are clearly no substitute for proper hand washing and everyone will see why it’s vital to wash hands properly.

Sadly, research shows that many people don’t follow that simple rule: but however you slice the evidence, habits formed in early childhood will play a significant part in encouraging good hand hygiene throughout life.