  Studies of the rotation-activity relation of late-type stars are essential to
enhance our understanding of stellar dynamos and angular momentum evolution. We
study the rotation-activity relation with K2 for M dwarfs where it is
especially poorly understood. We analyzed the light curves of all bright and
nearby M dwarfs form the Superblink proper motion catalog that were in the K2
field of view. For a sample of 430 M dwarfs observed in campaigns C0-C19 in
long cadence mode we determined the rotation period and a wealth of activity
diagnostics. Our study of the rotation-activity relation based on photometric
activity indicators confirmed the previously published abrupt change of the
activity level at a rotation period of ~10d. Our more than three times larger
sample increases the statistical significance of this finding.
