See if "germs" will grow after you've washed your hands - to be set up and monitored over a few weeks.
3 slice of bread (without preservatives if possible)
3 sandwich bags with seal
1. Label the bags CONTROL, CLEAN HANDS, DIRTY HANDS
2. Put an untouched slice of bread in bag marked CONTROL
3. Get everyone in lodge to touch one slice - palms and finger tips no need to press too hard - and put in bag marked DIRTY HANDS
4. Get everyone to wash their hands and put in bag marked CLEAN HANDS
5. Sprinkle a little water in each bag before sealing so bags are airtight
If you're brave enough, the experiment has also been done by wiping a surface (e.g. kitchen counter, toilet rim) and with a nose swab/finger up nose.
Google images for germ bread experiment.