I started with a discussion about how many living things there are on earth and how difficult it would be if there wasn't a way to sort them.
I presented the girls with a pile of buttons and asked them to select a specific one I needed without telling them which it was, this was obviously difficult to do. I asked them to sort the buttons by the 5 kingdoms (just like we sort living things into 5 kingdoms).
Then I selected the 'red' kingdom to work with and explained we would need to sort these further. For Phylum they decided to sort by no holes and holes,
for Class was number of holes, Order was transparent or not, Family was pink or red shades, Genus was if it had writing on and Species was the word written on it.
This all lead them to selecting the right button out of the hundreds available : )