What is the author's tone in Bluish by Virginia Hamilton?

Language is used as a kind of catharsis when Ms. Baker decides to explain the nature of Bluish's condition to her anxious students. Learning words such as "remission", "relapse", and the medical term for Bluish's condition, "Acute Lymphoblastic Leukemia", helps the students better understand Bluish, thus releasing the anxiety stemming from a lack of knowledge. The tone is both anxious and informative. At times the tone is dark but always with a sense of hope.