Drag the two points to the desired locations. The grid is scaled so that 1 gridline is a change of 2 in either the x or y directions. Points snap to grid points with integer values. The project will graph the line between the two points and give you the equation in slope-intercept form (y=mx+b). The slope and y-intercept will be rounded to the nearest 0.001. If you drag a point under the variables, you can retrieve it by clicking the green flag again.
