Lag B'Omer, the 15th day of the Counting of the Omer (the 7 weeks between Passover and Shavuot), has traditionally been a holiday celebrated out of doors, with picnics, archery contests, hiking, and all manner of nature activities. Here are some spring-into-summer books to put you in the right mood.

Crinkleroot's Visit to Crinkle Cove by Jim Arnosky. Aladdin Paperbacks/Simon & Schuster, $5.99. Ages 4-8

In case you missed him on public television, here's Crinkleroot, that white-bearded forest dweller, with his companion, Walking Stick, out hunting for their friend Sassafras the orange snake. If he's not mistaken, she'll end up down at Crinkle Cove "where the water always sparkles and cattails wave in the gentle breeze." There's lots to see and learn while following Sassafras' trail through the wet woods: animal tracks, wren houses, an oriole's nest hanging from a tree limb, blue heron, beautifully colored stones, and lots of frogs hiding among the tall grass. Children will enjoy this brightly illustrated picture book by author-illustrator-naturalist Arnosky, and it's just the thing to take along on a Lag B'Omer picnic.

Baseball Ballerina Strikes Out! by Kathryn Cristaldi. Illustrated by Abby Carter. Random House, $3.99. Ages 6-9.

Can a lively girl combine her loves of baseball (with a prankster coach who once came to practice in a gorilla suit) and ballet (with Madame, a teacher who doesn't get it jokes, like learning to do spins in the clothes dryer)? Especially when the mean Colby twins start harassing her on the way home and then show up at the play-off game, causing her home runs to turn into "strike-three-you're out"s? A good joke saves the day, and beginning readers will identify with the trials and tribulations of playing America's signature springtime game. Just right for reading in the car on the way to the school outing or a barbecue.

Baseball's Greatest Hitters. by S. A. Kramer. Illustrated by Jim Campbell. Random House, $3.99. Ages 4-9.

This new edition is the very thing for the statistics-hungry fan. Mark McGwire and Sammy Sosa take their places in the lineup with the very best record-holders in the category of "the hardest job in sports." There is also Ty Cobb, with the highest lifetime batting average; Babe Ruth, with the highest home run percentage; Ted Williams, only American Leaguer to win two triple crowns; Hank Aaron, who broke segregation in the big leagues and holds the first in total homers, total bases and extra-base hits. Terrific action photos of the greats whose single-minded determination to be the best hitter paid off. And there is an honest telling of the prices some paid to reach stardom. Keep this one in the duffel bag for instant inspiration before and in between at-bats, especially if your school is meeting another at the annual Lag B'Omer outing at the park.

Earth Magic: the Second Book in The Magic Elements Quartet by Mallory Loehr. Random House, $3.99. Ages 7-10.

Polly and her brother Sam step into another mystery, this time on their grandparents' farm. A rock just pops up right under their feet and there is a parchment note wedged underneath it with a very strange message about an "earth child" who needs to be taken care of and a warning to call in an emergency. So begins another chapter book for the curious. Those who know a bit about Greek mythology will have the upper hand with the clues. Polly and Sam find that caring for a stone, especially one that won't stay put, is a full-time job, complicated even further because their young cousin Audrey insists upon "helping," too. Just tuck the book in your backpack, nestle up against a tall tree in the shade, and then pull it out at dusk, while you are lulled into a false sense of security about the lovely woods just ahead. You'll never look at a rock the same way after this adventure!