Consider a regular, rectangular tank of water, of constant depth, in which the water's surface is initially still.
Now consider that you dip the end of a pencil into the water at regular intervals, say once every second, in order to make some transverse waves.
(1) Sketch a diagram to show four wavefronts.
(2) In which direction are the waves travelling?
(3) How does your diagram show that all the wave fronts are travelling at the same speed?
(4) Label on your sketch the wavelength of the waves.