The good, the bad and the ugly

As part of our Inquiry, we are now investigating germs (bacteria and viruses).  Today, we carried out an investigation to see why we need to wash our hands properly to avoid getting sick. 
First, we rubbed vaseline over the palm of our hands.  Then we pressed one hand into dirt and 100's and 1000's (no, we couldn't eat any!).  We tried to shake it all off but only some of it fell off.  Then we wiped our hand with a damp cloth.  Then we washed our hands with cold water.  Our hands were still dirty!
We worked out that by washing our hands with warm water and soap, we could get our hands really clean.