Drag the m and c sliders. The line y = mx + c redraws in real time.
y = 1.0x + 0.0
Controls
mslope1.0
cy-intercept0.0
Readouts
Slope1.0
y-intercept(0, 0)
x-intercept(0, 0)
Try a preset
What this teaches. Move c alone — the line shifts up and down, never tilts. Move m alone — the line tilts around its y-intercept. That's the whole idea behind y = mx + c.