Mosby, Robin and Barney are turned into nursery rhyme characters when Marshall has to make up a few stories to get his restless son to sleep on “How I Met Your Mother” (CBS at 8 p.m.). Marshall tells him the tales of “Mosby at the Bat,” “Robin Takes the Cake” and “Barney Stinson, Player King of New York City.”

SERIES PREMIERE: Get whisked into the vaults of the Smithsonian Institution on the first episode of the Smithsonian Channel’s four-part series “Seriously Amazing Objects” (8). This week, artifacts from America’s trailblazers are covered, from Lewis and Clark’s compass to the original Wright Flyer.

The team is challenged with an intense hostage situation on “Almost Human” (Fox at 8) that proves to be more rigorous than originally thought, while Maldonado weighs the options for conceding to the terrorist’s demands and saving the lives of innocent people.

SERIES PREMIERE: Country star John Rich is the host of “Rich at Night” (TV Guide at 8), a new talk show specializing in country stars, airing from his home in Nashville.

Max tries to make a good first impression on her first day of pastry school, but a class clown distracts her on “2 Broke Girls” (CBS at 8:30). Once Caroline gets word of Max’s attractive teacher, she pays a visit to the school.

The HBO documentary “Toxic Hot Seat” (HBO at 9) follows a courageous group of firefighters, mothers, journalists, scientists, politicians and other activists as they fight to expose a shadowy campaign of deception surrounding the real dangers of chemical flame retardants that left a toxic legacy in homes and bodies, and has taken nearly 40 years to unravel.

SERIES PREMIERE: In another effort to make a quality and heart-wrenching teen reality series, MTV is presenting the revolutionary new show “Generation Cryo” (10). The new docu-series is about kids who were conceived by an anonymous sperm donor and the issues they face as a new generation of young people.

Actor Josh Hutcherson comes to the “Late Show With David Letterman” (CBS at 11:35), with musical guest Sky Ferreira.

Actress Bette Midler is on “The Tonight Show With Jay Leno” (NBC at 11:35), along with musical guest Michael Bublé.

Pop star Demi Lovato and actor Emile Hirsch join “Jimmy Kimmel Live” (ABC at 11:35).

Rachel Lubitz