  Starting with two light clocks to derive time dilation expression, as many
textbooks do, and then adding a third one, we work on relativistic spacetime
coordinates relations for some simple events as emission, reflection and return
of light pulses. Besides time dilation, we get, in the following order, Doppler
k-factor, addition of velocities, length contraction, Lorentz Transformations
and spacetime interval invariance. We also use Minkowski spacetime diagram to
show how to interpret some few events in terms of spacetime coordinates in
three different inertial frames.
