My toddler and I are having a stand-off over a frog she found at the bottom of the garden. She wants to take it up to bed with her; I don't think I'm being unreasonable in refusing her request. "Why don't we wait until we go and stay with Granny?" I suggest. "We can find a new frog in her garden and Granny will let you take it to your bedroom."
My mother-in-law is the biggest animal lover I know. As a child she numbered a ferret and a baby crocodile among her pets, and over the years she has owned spiders, lizards, snakes and Madagascar hissing cockroaches. She was clearly destined for a life exploring the Borneo jungle but took a wrong turn and ended up as a boarding school teacher. Even there, her classroom contains a snake and a tarantula, and for many years she taught with an iguana perched on her shoulder.
It is a world away from my inner-city school, where the only non-two-legged life forms are a couple of goldfish residing in a tank of murky water in the entrance hall, which are discreetly replaced by the caretaker every time one of them is caught "sunbathing". Consequently, the slightest brush with the animal world - a wasp in the classroom, a squirrel in the playground - can send the entire class into a state of frenzy.
City children can be broadly divided into two groups: those who are covered in kitten scratches and spend their weekends walking dogs and burying hamsters in shoeboxes; and those who regard all animals with abject fear and have never come closer to the animal kingdom than a McDonald's Happy Meal.
One of our school governors once caused lunchtime pandemonium by bringing his St Bernard into the playground. Some children mobbed the dog, shrieking with excitement, one boy tried to ride it and others literally sobbed with fear as they dashed for the door and safety.
Even when you do all you can to prepare for a trip to a farm, you still end up explaining to children that the small white cows are also known as sheep and reassuring them that the baby chicks are highly unlikely to bite their hands off.
School trips these days involve numerous health and safety checks but a memorable trip from my own childhood always reminds me to do one extra check. It was a freezing cold March day at the rabbit farm. Left to roam free with the rabbits, we discovered that they liked Monster Munch crisps but not Wham bars. We let them nibble holes in our anorak sleeves and laughed uproariously when one of them peed down Seamus Reilly's trousers.
Finally, we left. We'd been travelling for at least half an hour when there was a disturbance at the back of the coach. As the teacher strode down the aisle, the news spread like wildfire. Soon the only child not chattering excitedly was Catrina Grey, who sat looking out of the rain-soaked window while a twitching nose and two bright eyes poked through the opening of her blue cagoule.
Jo Brighouse teaches at a primary school in the Midlands of England.