The teacher will graph a horizontal line and plot a point using TI-Navigator™, and the class will provide the points that create a parabola.

While using the TI-Navigator™ Activity Center for graphing and equation, the teacher graphs the line y = -3. Additionally, the teacher plots the point (0,-3). I recommend setting the coordinate increment at .25.

Once the line (directrix) and the point (focus) are visible on the graph, the teacher asks the students to plot a point that is located equidistant to the line (at a perpendicular distance) and the point.

Each student has to choose a different point, and these will be the students' best estimates.

With a little bit of luck and coaching, the points will begin to form the appearance of a parabola.

After activity is complete, have students try to estimate the equation of the parabola.

Continue this activity using different directrix and focus pairs, preferably ones that will not have a vertex at the origin.