Figure 2

When Johnny's homework behavior in math shows stability in the baseline behavior, on the seventh day the treatment variable is applied and his study duration increases.
When Johnny's homework behavior in science shows stability in the baseline behavior, on the twelfth day the treatment variable is applied and his study duration increases.
When Johnny's homework behavior in history shows stability in the baseline behavior, on the nineteenth day the treatment variable is applied and his his study duration increases.
Figure 2. Amount studied per day for math, science and history.