Disclaimer: This site is not here to attack all circuses, I enjoy going to circuses that don't exploit animals, however I do am against circuses that rely on animals to make a profit.
Although some children dream of running away to join the circus, it is likely that most animals forced to perform in circuses dream of running away from them. Colourful pageantry disguises the fact that animals used in circuses are mere captives forced to perform unnatural and often painful acts. Circuses would quickly lose their appeal if the details of the animals' treatment, confinement, training, and "retirement" became widely known.
Animals in cirucses are forced to perform degrading and unnatural acts, wearing silly outfits, for human pleasure. The training of these animals usually involves instilling fear in the animal by punishment for non-performance. They are transported around the country-side, housed in small cages, a far cry from their natural enviroments.
An animal advocate who worked undercover in a travelling circus was surprised that the circus was often unable to provide adequate water for the animals. Such entourages may visit 150 towns a year, and a clean water supply is not readily available in every location. As a result, drinking water is limited, and cleaning the animals and their cages may take low priority, causing a real hardship for animals like elephants, who normally bathe frequently. Food is often equally limited.
During the winter off-season, animals used in circuses may be kept in travelling crates or in barn stalls; some are even kept in trucks. Few circuses have the funds or the desire to put much money into comfortable winter shelters, since off-season housing is used for only a few months per year. Such unrelieved physical confinement has very harmful physical and psychological effects on animals: A study conducted by the Born Free Foundation found that confined elephants spend 22% of their time in abnormal actions, such as repeated head-bobbing or swaying, and confined bears spend about 30% of their time pacing.
I hope that this may provide you with a bit of an insite as to why animal circuses are an old barbaric tradition that in not safe or necessary. It does not provide children with the education on animals, for circus animals act different to ones in natural surroundings.
Speaking from personal experience as a child I was taken to a circus that had animal acts and although I enjoyed it at the time, I realise now how disgusting it was and if I had the choice I wish I had never gone. Because children don't understand what is really going on to those poor animals it is up to parents and friends to teach them so they don't grow up to regret things that they have done.