First of all it is a really easy activity. You can even do it with very young learners. You could use it as an ice-breaker in your first class. Some children find it difficult to start talking in a new situation, especially if they have to use their second language. So it could help ESL kids communicate if they pretend the dog who is talking and not them.
You can also use this activity to close a lesson after you read them the Dear Zoo! story.
They can choose different coloured paper to make their dog so it can be unique. Children can even name the dog and use it as a character of a role-play.
Give it a try!
Your ESL students learn and have fun at the same time!