According to the CDC, you should wash your hands for at least 20 seconds to be effective. Play a game that teaches kids about hand-washing by using a ticking timer to keep them interested. Buy a brightly-colored timer with a big bell and set it for 30 seconds. Get a child in position and set the timer. When it starts, the child should start scrubbing his hands vigorously, working up a good lather. As soon as the bell dings, the child should move to another sink to rinse and then on to dry while the next one goes to the sink. To make it more fun, you can also sprinkle glitter on the hands first to see who is washing most effectively.
For a game that gets your kids involved and talking, play true or false. Write simple questions about hygiene that will be easy for kindergartners to answer. Include topics like hand-washing, brushing your teeth or how often you should take showers. Gather your students around and read out the questions. Kids can yell out "true" or "false."
Boil eggs and put them in a dish of soda; leave it for a day and have each child take out an egg. Talk about the discoloration and how soda and food have the same effect on your teeth. Give each child a toothbrush and toothpaste and have them "brush" the egg to see how it comes clean. The process of seeing the dirty egg get clean can be a powerful visual example of the importance of brushing teeth. At the end of the activity, compare the eggs and see who has the cleanest one. You can talk about toothbrushing techniques to reinforce the lessons.
It is not uncommon to see young children cough or sneeze on their hands and then go about their business without washing them. For a fun game, clean the classroom bathroom thoroughly and cover the toilet with a garbage bag. Have your children pretend to sneeze and squirt washable paint on their hands to represent the germs. Then, ask them to wander around the bathroom and pick up objects you have set out in advance. The kids will see how the "germs" are transferred easily from object to object.