It's vacation time, so Emily has to write to her teacher to help when she discovers a blue whale living in her pond. Mr. Blueberry answers that she must be mistaken, because whales live in the ocean, not in ponds.

Throughout the summer, Emily and Mr. Blueberry exchange letters, until Emily has a happy surprise to share with her teacher. In the process, Emily learns a lot about whales. And Mr. Blueberry leans even more about imagination, faith, and love.
Dear Mr. Blueberry》就從一個小女孩Emily的奇想開始,Emily寫信給Mr.Blueberry 說她非常喜歡藍鯨,而且她昨晚在家里的池塘發現一只藍鯨,她想問老師關于藍鯨的知識. 然后,老師回信了,告訴她鯨魚不可能住在池塘,因為鯨魚活在咸咸的海水里. Emily又寫信給老師,說她每天早餐前會在水池里加鹽,她覺得鯨魚好像覺得好多了. Emily不斷地寫信問,老師則不斷地”糾正”Emily的觀念.,但是Emily卻不斷地寫信,開心地告訴老師她和鯨魚的友情,越來越好,藍鯨甚至愿意讓她碰碰它的頭. ......
有一天,鯨魚不見了,Emily寫信告訴Mr Blueberry,她有些傷心,不過老師還是以嚴肅的口吻告訴小女孩鯨魚不可能住在水池里.
但是,有一天Emily很開心地寫了一封信給老師:

小女孩最后還是保有了自己的想像,沒又被大人教化成為嚴肅只擁有知識而沒有想像的”乖小孩”.
而書中除了知識性的書信格式與自然生態的學習,兩邊書信的往來,大人的"合理世界"與小孩的奇想世界交錯著,正好讓閱讀者檢是自己的內在思維,我在閱讀的過程中,一直很好奇最后到底會如何?最后那封信讓我有一顆甜美的心情闔上這本書.

Dear Mr.Blueberry,
It’s been the happiest day! I went to the beach and you’ll never guess,
But I saw Arthur ! I called to him and he smiled.
I knew it was Arthur because he let me stroke his head.
I gave him some of my sandwich…..and then we said good-bye.
I should that I loved him very much
and , I hope you don’t mind ,I said you loved him,too.
Love
Emily(and Arthur)