This is the general guideline I use for shows. The age group I'm used to working with was from 3 to adult, you just need to adapt the details to suit the crowd
*Introduce the animal by name
*Have them guess what it is
*Tell them what it is (if they are right, if they arent correct them)
*Ask if they think it is full grown or not
*Ask where they think he comes from, environment and location
*What he might eat
*Cover things like lifespan, husbandry, captive requirements, safety when handling them, give reasons for everything
*Go into status in the wild and some of its habits in the wild and how it varies from that in captivity
*Question & answer period at the end of each animal
Main parts are just to keep the audience involved and not just you talking to them, have them ask questions at the end and always elaborate and go into detail about all points that you can. Express the amount of responsibility these animals are as well, and make sure you have all your facts correct