Everything you need to understand or teach Chasing Redbird by Sharon Creech.
Thirteen-year-old Zinnia Taylor lives in a rambunctious household. Three brothers and three sisters, all of whom seem to have a noisy way about them, push Zinny through the "dog trot" passage into the quiet sanctuary of the home of her Uncle Nate and Aunt Jessie and cousin Rose. Zinny and Rose are the same age, and she comes to think of Uncle Nate and Aunt Jessie as her second parents. Here Zinny is one of two children until the age of four when she gets whooping cough. Rose gets whooping cough, too, and dies. Aunt Jessie changes after her daughter's death and seems to live in a dream world.
When Aunt Jessie dies, Zinny begins to think that both deaths were her fault and takes on a burden of guilt. She is certain Rose caught whooping cough from her and that she has frightened Aunt Jessie so badly...