Ms. Keen wore a flower dress instead of orange polyester, and Melinda and the other students were surprised.

Melinda admires and pities Ms. Keen.  She feels that she could have been a doctor or a famous scientist, and instead gets stuck in high school.

Ms. Keen wore a purple dress with bright blue roses.  Baffling.  They shouldn’t let teachers change like that without some kind of Early Warning Alert.  It shakes up the students.  That dress was all anyone talked about for days. (p. 37)

Ms. Keen never wore the dress again, but it was a symbol that change is possible for Melinda.  She seems to respect Ms. Keen and listen to her.  She wants to learn.  This is significant because it is a biology class, where change is discussed. 

Through Ms. Keen, we see Melinda changing.  When Melinda shows a little apple seed to Ms. Keen, she gets extra credit.  Melinda thinks biology is “so cool.”  Something is finally engaging her in school.  Things begin to get better, especially when David Petrakis stands up to the history teacher and records and then videotapes the classes, so the teacher can no longer be racist and insensitive.  Melinda calls him her hero.

Ms. Keen gives Melinda hope.  She realizes that change is possible, both from a biological standpoint and from a figurative one.  Melinda begins to see the light at the end of the tunnel, and slowly turns herself into a stronger person and not a victim.