Three-year-old Derek Lineberry has the same problem each time he enters the Whitmore Library. He pauses in the middle of the turnstile, looking confused, and his older brother, trying to be helpful, flips the front bar down for him. Derek, however, doesn't move and another bar comes up behind and slaps him in the back of the head. Bonk.

Then Derek moves forward. He doesn't cry, either, especially not Tuesday night. It was his first night to attend Pajama Storytime, a free program of the Salt Lake County Library. He was dressed for the literary experience - wearing blue snap-up-the-back p.j.'s with his sneakers on over the pajama feet, "so the feet won't get worn out in the parking lot," his mother explained.Derek headed for the Rainbow Room in the quietest corner of the children's section. There, librarian Joan Steneck reads, tells stories and does simple crafts with 20 children every Tuesday night at 7 p.m.

Maegan Steiner arrived with a nightcap that matched her gown. Jared Maxwell brought his panda

Stephanie Rick chose a pink nightie and bunny slippers and carried a stuffed cat. "What I like best about this library is that they let you bring any animal you want," she said.

Reading bedtime stories to this many 31/2- to 5-year-olds could be an exercise in frustration and raised voices. Steneck reigned calmly, though. The children really listened.

"You have to start with the longest story first," she explained. "Then vary the pace with some finger play, a shorter story, a little dance." The subject for Tuesday's story time was St. Patrick's Day. Steneck read about leprechauns, recited a poem about shamrocks, and mixed blue and yellow water to "magically" produce green. She read a funny story about green pickles. Steneck has given daytime story hours for 13 years, but found that children are quietest in the evening, especially when they have their pajamas on. Their parents agreed, saying that no matter how excited the children are to dress in their best nightwear and hurry to the library, they come home relaxed and ready to pop into bed.