1. The problem is to graph the point $(-1, 2.5)$ on the coordinate plane. 2. The coordinate plane has two axes: the horizontal axis is the $x$-axis and the vertical axis is the $y$-axis. 3. The point $(-1, 2.5)$ means we move 1 unit to the left of the origin (because $x=-1$) and 2.5 units up (because $y=2.5$). 4. Plotting this point involves locating $-1$ on the $x$-axis and $2.5$ on the $y$-axis, then marking the point where these coordinates meet. 5. This point lies in the second quadrant of the coordinate plane because $x$ is negative and $y$ is positive. 6. The graph visually confirms the point's position at $(-1, 2.5)$.