In a high school public speaking speech, do you need to enforce an opinion?

For example, I'm writing a speech on 'The Role of The Modern Zoo'. My public speaking teacher is saying that I need to enforce a message, like that humans would be better people if we cared for animals more (I know that doesn't really have much to do with the role of the modern zoo but that's what the teacher suggested). In primary school, I was twice public speaking champion of the school *hooray* and I never needed a message. Help?