Claire Robinson, an education officer at London Zoo, finds that children react positively to animals. She used to take snails into class to watch them move on glass, and find children naming them, treating them with respect and even letting them crawl over their faces. She says that how adults react has lots to do with it.
Not everyone agrees on what animals ought to be in school. Some are happy with woodlice and snails which can be returned home a week later without distress. Some are happy with captive-bred creatures. There's a dimmer view on keeping furry mammals, or bringing monkeys, birds of prey and big cats into the classroom.
But there is agreement on what we can learn from animals after guidelines and consciences are followed. For some, like headteacher Rachel Popham, caring for creatures, keeping them and learning about them is part of school. And when she joined St Mary's Primary in Leicestershire she brought not furry rabbits but her troop of stick insects and snails. "It was something I used as a way of relating to the children," she says.
Over the years, she has brought in a skink, a cockateel, tree frogs and corn snakes, talking for example, about classes of animals. They have seen and talked about the salamander's poisonous skin and tried to talk about a pair of chameleons who started their colourful mating during the lesson, dancing beautifully and rivetingly.
Mrs Popham feels that their stick insects make a superb case study, with their large features and feeding habits. "You can see them shed their skin, see their camouflage, and for reproduction, you start off with two and look how many you get." Otherwise, they are easy to look after, and at St Mary's they live at the entrance rather than suffer classroom noise.
For the holidays she will train willing parents or take the creatures home herself. Some parents' offers go awry, like their shoal of minnows that a big fish ate. Or the locust eggs that hatched in an airing cupboard and caused havoc.
Maybe it takes an enthusiast and an expert like Rachel Popham to do this with confidence. Some of us might benefit from an expert introduction and this is where guided visits to farms, zoos, pet shops and the wild come in. There are also experts who bring a sensible choice of animals to school. They are hard to track down and are best found through recommendation.
Vic Taylor and his Mynewt Enterprises offers a choice of themes for your animal encounter. There are sessions on food chains, habitats and classification. Under the topic Animal Colouration he will talk about camouflage for defence and attack, colours that warn predators as well as deceive them. Under Movement he will talk about climbers and jumpers with and without feet, and how they find food and avoid being food.
Vic Taylor will bring a crew of cold-blooded, captive-bred animals, and in this work these are conscience words. There are snakes, millipedes, giant snails, tree frogs, and the almost delightful, almost "varnished" as the kids say, hissing cockroach. He makes no promises, because if the snake has just fed, it's not brought.
As a long-serving environmental education teacher, he is ready for the responses of the animals and children. "I get the children to pretend they are stuck to their chairs. I also offer to work in class rather than in the hall, because the children are more settled and I can relate ideas to the work they are doing."
Rachel Popham talks about herself as doing a bit of missionary work for lesser creatures. She sums up her policy thus: "If animals are bred in captivity, looked after well and children are taught to respect them, not to shout at or maul them, then I think you're doing more good for the species than harm. "
And Frazer Swift, education adviser at the RSPCA gets the last word, reminding that besides considering children's and animals' welfare, an aim for schools is to develop a positive, responsible attitude. A stick insect is for life.
What to keep
There is more to class pets than rabbit and guinea pigs. There are creatures you can keep, and keep your conscience as you do. Each has a fascinating, exotic life story and without worries about asthma and children's health. In fact the advice from experts, Small Life Supplies, is to attend to washing hands and such like.
Stick insects are unusually easy to keep with the caveat that they should not be allowed to overbreed. Some eucalyptus or bramble leaves, a daily spray of water and a weekly cage clean doesn't add up to much cost or a holiday chore.
For learning about creature features, the stick insect is special. It is large enough to be seen well and rather than bite or attack, it has evolved clever ways to escape predators - like the pink-winged variety which can just about fly to save its life or the classic-looking Indian variety, which flashes its red leg tops to fool predators that it is dangerous. When alarmed, they smartly pull in their legs and fall like a thrown stick. Blow gently over them and they'll stand up again.
Amazingly they grow by shedding their outer skin and the insides of the breathing tubes, too. They do this six times in five months and they get fat and stop eating as they approach their "time of the month". This 10-minute spectacle leaves behind an impressive figure of their former self which they will often make a meal of.
A favourite is the Macleays Spectre, a bulky creature with leaf-like legs and a scorpion-like tail which is both awesome and well-camouflaged. There are males which fly and females which don't, unlike some other types of stick insect where there's just one sex. They don't even need to mate to lay eggs and breed. They will do this with no help, leaving a new generation when they die a year on.
A more sedentary classmate is the shiny brown Giant African Millipede. It moves by regular waves of its legs and grows by bursting out of its plastic- like skin. Males have two legs less than the female but you can also tell them by the gap in their line of hair-like legs.
They co-operate with the gorgeous yellow and black African Fruit Beetle which helps to clean the millipede's legs, in return for helping it back on its feet after a fall.
The beetle's life cycle is more dramatic than most. It mates and lays eggs. These turn into large grubs which make a hard egg case, out of which hatches a beetle. A slice of orange will keep it happy, but make it unhappy and it squirts at you messily.
For something almost soporific there is Achatina, the giant snail that grows so fast you can see a new band of shell grow daily.
You will find more. Children can watch caterpillars turn into Tortoiseshell butterflies or see the amusing "sea monkey" swim (Artemia - a crustacean not a monkey) but always with its back against the light. There is a lot of learning about animals to be had.
WHERE TO GET THE WILDLIFE - AND ADVICE ON HOW TO KEEP IT
* Most of these creatures are available through aquarium and pet shops as well as direct from specialists such as Small Life Supplies.
* Keeping Stick Insects by Dorothy Floyd, the definitive book, is available through Small Life Supplies, tel: 01949 842446 * The RSCPA's Animals and Education sets out the society's guidelines on animals and encourages schools to develop an animal-friendly policy. It was sent to school governors earlier this year. The RSPCA also has excellent pet care leaflets, an education newsletter and a network of education officers. For details contact the RSPCA, tel: 01403 264181 * Many zoos have a schools' programme. London Zoo, for example, offers a range of topic packs, classroom ideas and illustrated talks for school parties. Contact the Education Dept, London Zoo, tel: 0171 449 6552 * Vic Taylor's school programme catalogue is available from Mynewt Enterprises, tel: 0181 805 0745
* Subscribing schools can get advice from CLEAPSS at The School Science Service, Brunel University, Uxbridge UB8 3PH.