School is out for the summer. But "Someday School" is in session for a 13-week semester of sorts.

This "School" is not as smart as many of its PBS preschool classmates, but it certainly makes the grade for diversity, with six distinctive shorts woven into each one-hour lesson (Sundays at 6 a.m. on WETA and 7 a.m. on MPT).

Keeping the program on track is Mrs. Apple, who gently guides the young viewers through the segments by reinforcing themes and content. She also leads the interactive visits with grade-school teachers throughout the country, helping orient children about what the first day of school is like, what classrooms look like, where students eat lunch and other kiddie concerns.

"If you're putting on a show for preschoolers, it has more value if it has some education behind it," said Cathy Shambley, the portrayer of Mrs. Apple and a writer for the short "Nounou Time." However, she added, "you don't want to lose the entertainment value."

"Someday School" is meant to introduce school-related concepts to children, who ideally will then involve their parents in a conversation about what they saw, Shambley said.

Shambley, active with the Los Angeles-based Groundlings Comedy Improvisation Theatre and a writer for episodes of "Casper" and "Pinky and the Brain" -- the one where Pinky surprised Brain with a birthday party -- said much of her inspiration in kids TV comes from her three children, ages 3, 13 and 18.

Likely only the youngest viewers will linger long with "Someday School." Although Hollywood Ventures invested a reported

$3.4 million in the production, the series occasionally has an inexpensive infomercial feel.

However, there is much to see in the constantly changing series that is both new and somehow familiar (especially to viewers of segmented animated programs such as "Big Bag" and "Small World").

The parts:

"Nounou Time" is a puppet series that uses a bear (Nounours) and clock (Timothy Timekeeper) to help children adjust to morning and night-time routines. The morning version includes tips about bed-making and planning ahead; the night version touches on teeth brushing and preparing for bed. These new three-minute segments are based on the series "Bonne nuit les petits," a top-rated preschool series in France for 35 years. Music is provided by Jeff Barry, songwriter of hits such as "Chapel of Love," "Da Doo Ron Ron" and "Sugar Sugar."

"Humphrey B. Bear" lives in a magical tree house with his human friend Tess. His daily singing, dancing and playful adventures are meant to parallel the needs, fears and fun of preschoolers. The 12-minute live-action segment is based on an Australian series that has run for 30 years.

"The Slow Norris," a 10-minute puppet segment, features an innocent cave-dwelling creature who is introduced to the outside world by a 6-year-old girl, an energetic worm and a slightly grumpy beetle. The voice of the girl, Allie, has been re-done for an American audience from the series that appears on ITV, Britain's largest commercial network.

"Oakie Doke," a 10-minute model animation segment from the BBC, purports to teach social and life skills through stories involving a leaf-covered character and the families of playful frogs, mice, hedgehogs, moles and squirrels that live in Oakie Hollows.

"My World" uses wildlife footage and computer animation to introduce viewers to natural history. The 10-minute segments, fashioned like a game show, are produced in New Zealand and have a companion magazine for children and parents.

"Wiggly Park" is a five-minute computer animation segment starring a community of creatures that wiggle, slither and buzz around a town park. The problem is human contact, no matter how well intentioned. The series is culled from 500 original episodes that have aired in London, based on a BBC Radio series.

Nickelodeon, which itself has been copied in recent years by its competitors, borrows a strategy from Cartoon Network this week with the premiere of "Oh Yeah! Cartoons!"

The half-hour series debuts Sunday at 11 a.m.

Created and produced by Fred Seifert, "Oh Yeah! Cartoons!" will introduce three new characters each week in a variety of animated styles.

The format is three seven-minute cartoon shorts, following in the tradition of Looney Tunes and, most recently, Cartoon Network's World Premiere Toons.

The first episode features the shorts "Chalkzone," about a schoolboy who finds a magic stick of chalk that allows him to enter a world where erased chalk drawings come to life; "What Is Funny?," the adventures of Slap T. Pooch as he tries to unravel the mysteries of humor; and "Jelly's Day," featuring a little girl with a monster cousin from Entransylvania.

Seifert is the former president of Hanna-Barbera, which was involved in the production of shorts for World Premiere Toons.

The project's 17 creators range from recent high school graduates to 30-year industry veteran Larry Huber. Many formerly worked on Cartoon Network projects -- most notably Bill Burnett, a former story editor and music writer for "Cow and Chicken" who is involved in eight Nickelodeon shorts, including all three featured in the premiere, and Butch Hartman, former director for "Dexter's Lab," "Cow and Chicken" and "Johnny Bravo."

Fox last month launched a 10-part public service campaign targeting the social and emotional needs of pre-teens.

In the 30-second and one-minute "Check Yourself" spots, the cast of six diverse kids depict problems relevant to 8- to 12-year-olds and offer coping tools to help alleviate anxiety, anger, stress or peer pressure.

Among the tips: Stop, breathe and count to three when dealing with anger or anxiety; and "Draw It, Write It, Let It Out," promoting artistic endeavors to express and defuse strong emotions.

Not to worry, though -- take a deep breath . . . one, two, three -- Fox's money-making Power Rangers will continue to settle differences the old-fashioned way. CAPTION: One-hour "Someday School" includes short programs "Here's Humphrey," above, and, from left, "Nounou Time," "The Slow Norris" and "Oakie Doke." ec CAPTION: "Chalkzone" is included in the premiere episode of "Oh Yeah! Cartoons!" ec