The idea of this activity is to keep the tuberculosis infection from taking over your body.
Imagine . . . your doctor has just found tuberculosis infection in your body. "Not to worry," he says, "just take these pills every day, until I tell you to stop."
Now, the TB germs are going to try to take over your whole body, and you must keep them in the O.K. zone (blue) and out of the DANGER zone (red), using the pills that the Dr. has given you.