Tacky the Penguin is an odd bird to say the least. All the other penguins are perfect and similar, but Tacky doesn't follow them. One day some hunters come along to catch some pretty penguins. All the penguins hide, except Tacky. He greets them and marches, dives, and sings for them. The hunters can't take anymore so they run off. All of the other penguins are very glad they have Tacky.
I would use this book to drive home the point that being different is okay. I would most likely use it with younger grades, at least up to third grade. For a lesson, I would have the students answer questions and discuss parts of the book. The questions and analysis would be dependent on the grade.