The early Saturday-morning air was damp and chilly. Jack sat on his front porch steps. His chin was cupped in his hands.  Annie came out the front door.  "Do you want Mom to take us to the rec center now?" she asked. It was the day for baseball tryouts.  "I've decided not to go," said Jack.  Annie sat down next to him. "What's wrong?" she asked.  "I can't stop thinking about last season's tryouts," said Jack. "I fell down when I swung the bat. Everybody laughed."  "Yeah, well, everybody laughed at me, too," said Annie. "Remember, I threw the ball to the wrong team."  "So maybe neither of us should go," said Jack.  "But our whole family loves baseball," said Annie. "We read about it. We watch it. We learn batting averages. We--"  Before Annie could finish, something dropped from the sky and rolled across their front yard.  "What's that?" said Jack. He and Annie ran down the steps.  A small white ball lay in the grass. Annie grabbed it.  "It's a baseball!" she said.  "Where did it come from?" said Jack.  He and Annie walked to the sidewalk and looked up and down their street. No one was there.  "Maybe it's from another world," whispered Annie. She handed the ball to Jack.  "That's crazy," said Jack. "What other world?"  "Think about it," said Annie. "One second, we're talking about baseball--and how we don't want to go to tryouts. The next, this baseball drops from the sky!"  "Oh. You mean--" said Jack.  "Morgan!" Jack and Annie said together.  Annie took off down the sidewalk. "Let's go!" she called to Jack.  "Hold on!" Jack shouted. He put the mysterious ball inside his backpack and raced after Annie.  Jack and Annie crossed the street and dashed into the Frog Creek woods. They hurried between the trees until they came to the tallest oak.  The magic tree house was back.  "Yay, team!" said Annie. She grabbed the rope ladder and climbed up. Jack followed her into the tree house.  Leaf shadows danced on the wooden floor. Two gray baseball caps sat in the dappled light.  Next to the caps was a book: history of baseball. A red leather bookmark was sticking out from the pages.  Jack picked up the book and opened to the bookmark. The page showed a photo of a baseball stadium. The caption beneath it said:  Ebb e ts Fi e ld, B rooklyn, Ne w Y ork, April 15, 1947  "Ebbets Field?" said Jack. "I've heard of that. It was a famous ballpark."  "Look, there's a message on the bookmark," said Annie.  Jack held the bookmark up to the light.  "It's Morgan's handwriting!" he said. He read aloud:  'Twas a big day for baseball  So many years ago.  Journey to Ebbets Field  To learn what you should know.  "Learn what we should know?" repeated Jack. "To become better ballplayers?"  "Sounds like it!" said Annie. "Morgan must have known about the tryouts." She read the next verse:  These caps are magic  Made only for you  To give you the skill  To know what to do.  "Oh, man, it sounds like these caps will make us great players!" said Jack.  "Yay!" said Annie. She read on:  As long as you wear them  All others will see  The skillful people  You're pretending to be.  "I get it! Everyone else will see us as great players!" said Annie.  "In a Little League game?" said Jack.  "Why not?" said Annie. "Little League teams must have played at Ebbets Field, too."  "Yeah, probably all kinds of teams played there," said Jack.  Annie read more:  When you hear the final score,  Give the ball with the name  To the one who knows best  The rules of the game.  "Our baseball has a name?" said Jack. He pulled the ball out of his pack and turned it over in his hands. "No name here."  "Well, maybe we're supposed to give it one," said Annie. "How about Ballee?"  "Ballee?" said Jack. "I don't think so."  "Okay, okay. How about Fly Ball?" said Annie. "It flew down to us."  "Fine, whatever," said Jack. He put Fly Ball back into his pack. "Ready?"  "Yes! This is going to be so much fun," said Annie.  Jack pointed at the photo of Brooklyn, New York. "I wish we could go there!" he said.  The wind started to blow.  The tree house started to spin.  It spun faster and faster.  Then everything was still.  Absolutely still.    Excerpted from A Big Day for Baseball by Mary Pope Osborne All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.