This is a book that pops up on many lists for teaching character. Simply put this is a book about life. Life in a short picture book. If that's possible.
Put these questions to your students:
Are you going to approach life with optimism?
Are you a pessimist at times?
Perhaps discuss the meaning of both of these words, regardless of age!
You can address so many character traits with this book. Other than optimism, you can also discuss perseverance, caring, being confident...
For those of you who have a theme that you revisit throughout the year, I can see the phrase 'Not yet they don't' being a great mantra for your students who grow and develop through the school year.
For a class that is just learning how to do reading responses, this is a great first month read. You can do shared responses on anchor charts and leave them up all year. Revisit them to discuss how to do a proper reading response but also revisit the message of the book. Not only will it be a good example of how to write a reading response but this story will underline what your students should say to themselves when they feel they can't do something
Not Yet They Can't!