Teachers (10:30 p.m., TV Land) – In the fifth episode of this new comedy series, Ms. Watson considers that her ex may have moved on, and Ms. Cannon tries to put an end to cliques among teachers.
Also on tonight . . .
Mysteries of Laura (8 p.m., NBC) – Valentine's Day takes a deadly turn when Laura thinks a long-dormant serial killer has re-emerged.
Supernatural (9 p.m., CW) – While investigating a set of murders on Valentine's Day, Sam and Dean find they are dealing with an ancient curse that causes victims, once kissed by it, to die.
black-ish (9:30 p.m., ABC) – When Dre realizes that his neighbor hasn't invited any members of his family to her pool parties, he thinks she assumes they can't swim.
Younger (10 p.m., TV Land) – When their first author is a handful, Liza and Kelsey worry their imprint might be over before it begins.
Code Black (10 p.m., CBS) – Christa feels insecure when Neal's ex-girlfriend returns to the hospital after a year of volunteering in Haiti.