
I checked the landscape nervously.
"What about Running and Hiding? It sure would spoil my day to get eaten by a dinosaur."
"No, no, no," said Sam. "Brainpower. Dino-saurs and cavemen never lived at the same time." Sam adjusted his leaf. "If this
is 40,000 b.c., dinosaurs have been extinct for 65 million years. Cro-Magnon man, our direct ancestor, should just be replacing
Neanderthal man."
Sam paused. And at that very second we heard a terrified human scream.
"Aha! Man," said Sam.
But then we heard another sound. It was a roar. A very large roar. The kind that comes from a very large, angry, and
hungry animal.
"I think it's time for a disappearing act," I said.
"You can do that without The Book?" asked Sam.
"Sure," I said, diving behind the nearest fern.
Fred and Sam followed just as a bunch of wild-looking men crashed out of the bushes. They wore raggy skins, had long
scraggly hair and
beards, and were running as fast as they could.
"Cavemen," whispered Fred.
The tops of the bushes shook, and the animal that was chasing them stuck out its head.
"Dinosaur," whispered Fred.
"Impossible," said Sam. "Dinosaurs are extinct."
The big scaly head turned its beady eyes to-ward us and roared.
We backed against the rock wall.
"Why don't you go explain that to him," I said. "Then maybe he'll go away."
The dinosaur looked at us and roared again.
We went to the Stone Age to become kings, and were about to become lunch.
TWO
But, I'm getting way ahead of myself (or really about 42,000 years behind). Let me explain.
My best friends Sam and Fred were hanging around at my house after school as usual. We were trying to finish some
annoying math home-work—very unusual. If it hadn't been pouring rain, we'd have been long gone.
"I've got a great idea," said Sam.
"I don't need any great ideas," said Fred. "I need the answer to problem 14: 'If Mr. Sleeby walks at an average speed of 2.5
miles per hour, how many miles does he walk in 4 hours?' "
"2.5 miles per hour times 4 hours equals 10 miles," said Sam. "You see, our problem is we've been going about this
time-travel business all wrong. We haven't been using our brains."
I looked up. "What do you mean?"
"Well, I've been doing a little research, reading time-travel books—Half Magic, Narnia stuff, A Wrinkle in Time, and The
Time Machine."
"Hey, I saw that movie," said Fred.
"And do you know what people in those books always forget?"
"Food," said Fred. "They never eat in those books."
"No, you Neanderthal," said Sam. "They never pack anything useful to take with them. Like King Arthur would have been
amazed by this calculator. The Cheyenne would have been wowed by a Walkman."
"And Blackbeard would have loved an F-16," said Fred.
Sam frowned. "I'm serious. If we just take the right ordinary stuff, people will be convinced we're magic."
I put down my pencil. "But I just learned this great trick," I said. "Watch me roll this straw across my desk using only the
invisible powers in one finger. I won't touch it. Watch. Hocus, pocus, straw move-ocus." The straw rolled across my desk with
my finger just behind it.
"That's very magical," said Fred. "Especially the way you blow the straw so it rolls."
"You weren't supposed to see that," I said. "I told you to watch my finger."
"But one detail I haven't exactly figured out," continued Sam, "is how to take The Book with us so we can get home
whenever we want to."
"You call that a detail?" said Fred.
"But I think the trick might be to just hang on to The Book right when that green time-traveling mist starts to swirl around."
"It sounds almost too simple to be true," I said.
"Sometimes the best ideas are the simplest," said Sam. "The ancient Greek mathematician Archimedes discovered he could
move the world