"No Mum, *I'll* do the sums and *you* do the answers."
It worked very well actually. Duplo (the nearest county thing I could find) worked very well when I ran out of available fingers.
We were doing fine until it came to one-shared-by-three, then we reverted to chopping up a slice of bread and sharing it around three of us.
"No, we've still all got one piece each.." said Lyddie, quite truthfully.
I think we'll leave the concept of thirds to another day. Good excuse to bake a cake ;-)