Germs are everywhere. Each object or surface you touch has likely been touched by a person or object that has been contaminated by germs. Teaching children about germ growth through demonstration encourages them to fight the spread of germs through washing their hands and keeping work and play areas clean. Bread possesses yeast and sugars, making it the perfect surface for an instructive germ growth demonstration.
Introduction to Germs
Talk to your children about germs: what they are, how they are spread and both the good and the bad aspects of them. Have a volunteer use lotion on her hands, then sprinkle a little glitter on one of her palms. Ask the volunteer to act normally throughout the day. At the end of the day, take note of where the glitter ends up. It will be on other people's hands, lunch boxes, books and other objects. Discuss how germs are spread in a similar manner. Challenge your children to guess what might happen when unwashed hands come in contact with food.
Label four zippered plastic sandwich bags as follows: "Control," "Cough," "Touch" and "Contact." Use tongs to place an untouched piece of wheat bread in the "Control" bag. Have a child cough on a piece of bread and place it in the "Cough" bag. Have a child rub his palm across the flat surface of a piece of bread and place it in the "Touch" bag. Lastly, rub the flat surface of a piece of bread on a desk, counter top or other surface and place it in the "Contact" bag. Use a spray bottle to add a spritz of water to each bag, then seal the bags. Place all four bags in a dark, warm location, such as a cupboard.
Ask your children to predict what will happen to the bread as time passes. Have your children examine the bagged bread daily and record any changes. For best results, ask children to keep a written log containing a category for each of the bags of bread. Mold will begin to form on the bread after a day or two, but the amount of mould that forms will vary according to the contamination of the bread. Have your children observe the bagged bread and the changes that occur for one to two weeks.
Ask your children what their opinions are on the changes that have occurred. Challenge your children to explain why the changes they observed took place. Discuss how germs grow and multiply and the conditions that allow germs to thrive, such as warmth and sugar. Ask children to explain how to reduce germ growth by methods such as washing hands and sterilising surfaces.