I might even delve deeper into natural history and say, 'The periodical cicada spends six years as a grub underground, and no more than six days as a free creature of sunlight and air.
Your son Wilfred has spent six years as a grub in this school and we are still waiting for to emerge from the chrysalis.'
A particularly poisonous little girl might sting me into saying, 'Fiona has the same glacial beauty as an iceberg, but unlike the iceberg she has absolutely noting below the surface.' I think I might enjoy writing end-of-term reports for the stinkers in my class. But enough of that. We have to get on.