That morning the sky was a shiny blue, with a round, warm sun that looked like a giant omelette hanging in the air. Dash, Ziggy, Lily, and Skye had made up a brand-new game: the shadow race. You had to jump on a friend's shadow before it ran away, and whoever did it won a point and a laugh.

"You'll never catch my shadow!" shouted Dash, who dashed as fast as lightning with his shoelaces a little untied.

"Wait, wait, I'm coming!" answered Ziggy, hopping like a spring.

Lily never gave up and chased everyone with her head down. Skye, calm and gentle, laughed with her mouth wide open and tried to catch the shadows with her hands.

But just as Dash was doing his very best cartwheel, something strange happened. Big lazy clouds began to push into the sky, one on top of the other, like piled-up pillows. Push here, push there, they covered the whole sun. The meadow turned grey. The shadows vanished. And without the sun, the game did not work anymore.

"Aww," huffed Dash, "where did the sun go?"

That was when, from far away, a familiar sound arrived. CHOO CHOO! Out of the grass popped Toby the Magic Train, with smoke that made funny little rings and colorful cars that bounced along.

"CHOO CHOO! Hello children, hop on with a grin,
we're off to the branches where games can begin!
A sad little tree has forgotten to play:
just run, and say thank you, and magic will stay!"

The children looked at each other with shining eyes. A tree that doesn't laugh anymore? Running? This sounded just like a job for Dash. They all climbed aboard, held on tight, and off they went! Toby set off, rattling happily, up and down the hills, all the way to a wonderful place.

In front of them stood the Great Round-Dance Tree: an old, very tall tree, with wide branches open like arms ready for a ring-around dance, and a hollow trunk so big a whole team could hide inside. But that day the tree was grey and dull, with sad leaves drooping down like floppy ears.

Suddenly, from a branch, came a tumble. Legs in the air, leaves flying, and a soft thud in the grass: PLOP! It was a little fawn, with heart-shaped spots on his coat. He got up, took two steps, and tripped again over his own legs.

"Oops! Sorry! Hi! Oops, sorry again!" he said, laughing. "I'm Tumble. I make friends with everyone, but I always fall. My legs argue with each other!"

Tumble smelled of sweet blueberries, and whenever he got excited a very funny sneeze escaped him: ACHOO! And out of the sneeze flew lots of colorful petals that fluttered in the air.

"But why is the tree so sad?" asked Skye in her gentle little voice.

Tumble lowered his ears. "Because the Sun has hidden above the clouds. You see, the Sun gives us light every day, but nobody ever says thank you. So he felt lonely, he sulked, and he covered his face. We have to be grateful to him."

"Grate... what?" asked Ziggy, scratching his head.

"Grateful," repeated Tumble. "It means saying thank you with your heart to someone who is kind to you. Like when your mommy makes you a snack and you say thank you and give her a little kiss."

"Ah! Now I get it!" said Ziggy.

"And how do we say thank you to a sun hidden way up high?" asked Lily, with determined eyes.

Tumble pointed to the highest branch of the tree, the one that almost touched the clouds. "We have to build a path of light all the way to the top. A path made of shiny leaves and sparkling pebbles. If we get up there and shout thank you all together, the Sun will hear us. But the leaves are down low, and the top is far away. And my legs... well, you've seen my legs."

Dash rubbed his hands together, so happy. "A path we build by running up and down the branches? But this is a RELAY RACE! The most fun thing in the world! I've got this!"

And he explained the plan in a real champion's voice: "We line up along the branches. The first one grabs a shiny leaf down low, runs, and passes it to the second. The second runs and passes it to the third. Leaf after leaf, we climb to the top and build the path. Reeeady? GO!"

The relay began, and it was so funny. Dash shot off like a rocket, but the branches were wet from the Singing Rain, that special rain that makes music as it falls on the leaves: PLINK, PLONK, PLICK! Dash slid as if down a slide, spun around three times, and ended up sitting in a puddle. SPLASH!

"I made it... almost!" laughed Dash, all soaked, with a leaf on his head like a hat.

Everyone burst out laughing. Then it was Tumble's turn. He took the leaf, took two sure steps, and then, PLOP!, he tripped and rolled like a ball of fur along the branch, scattering blueberries and leaves everywhere. He stopped hanging upside down by his tail.

"Everything's fine!" said Tumble, swinging. "At least from here I see everything upside down!"

Lily grabbed the leaf and ran fast to the next branch. Then Skye, calm and gentle, lined up the little pebbles one next to the other so they would sparkle nicely. And the path began to grow, one little piece at a time, climbing up the trunk of the tree.

But at every turn there was a new gag. Once Ziggy passed the leaf to Skye, but the leaf was too slippery and flew off in the wind, and the two of them bumped into each other with a DOING! bouncing backward. Another time Tumble, so excited that the path was rising, let out a giant sneeze: ACHOO! And a cloud of petals covered Dash's eyes, so he ran straight into the trunk, BONK!, and saw little stars even without the sun.

"Ow ow ow, what a laugh!" said Dash, rubbing his nose. "But we have to hurry!"

Because now the tense moment had come. The sky was getting darker and darker. The clouds turned black and big, and the darkness began to eat the tree from the bottom. It was a little cold, and the last piece of path was still missing, the one up to the highest branch.

"We'll never make it in time," whispered Tumble, and his ears drooped down sadly. "It's all my fault. I always fall, I ruin everything. I'm no good at all."

He curled up in a corner of the hollow trunk, tiny and small. Dash stopped short. He looked at the darkness rising, looked at his sad friend, and then he did something a true champion would do: he went to Tumble and put a paw on his shoulder.

"Tumble, what are you saying? You're the strongest of us all!" said Dash. "Do you know why we climbed so high? Because every time you fall, you make us laugh, and when we laugh together we get faster. And look: your sweet-smelling petals made the path the most beautiful in the world. We'll do the last part together. It's your turn to start!"

Tumble raised his ears. His eyes grew shiny, and this time the sneeze was the biggest ever: ACHOOOO! A fountain of colorful petals rose up high and landed right on the last piece of branch, like a sparkling trail.

"Look!" shouted Lily. "The petals made the last piece of the path!"

It was true. The path of shiny leaves, sparkling pebbles, and sweet-smelling petals reached all the way to the top. The children and Tumble climbed the last stretch all together, fast, while the darkness came just one step away from their paws. A final sprint, the last jump, and... there they were on the highest branch, the one that touched the clouds!

"Now!" said Dash. "All together! One, two, three!"

And they shouted with all the breath they had: "THAAANK YOU!"

The thank-you flew up together, strong and warm, and tore through the black clouds right in the middle. A sliver of light, then two, then many. The clouds opened like curtains at a window, and the Sun popped out, round and happy, with a huge smile and rays that danced.

Right away the Sweet-Scented Breeze came back, that gentle little wind that carries the smell of flowers from far away. The Great Round-Dance Tree lit up all over: the leaves turned green and shiny again, the trunk glowed, and the branches really did look like open arms ready to hug everyone.

"We won the most important relay race in the world!" cheered Dash, jumping into the air.

Tumble sneezed with joy one last time, ACHOO!, and made a rain of petals fall on everyone, laughing. He didn't feel useless anymore: he felt like a champion, just like his friends.

As the sun warmed the meadow again, a familiar CHOO CHOO was heard. Toby the Magic Train had come back to fetch them. They said goodbye to Tumble with a big hug, promised to come back, and climbed onto the cars.

"CHOO CHOO! What a race, what big jumps, what a cheer,
a loud, happy thank you stays right in your ear!
The sun is back shining, so happy and bright:
a warm-hearted thank you makes everything light."

And as the tree waved with its branches in the wind, the children understood something very sweet, without anyone explaining it to them: saying thank you is not just a word. It's a magic that warms the heart, brings the sun back, and makes both the one who says it and the one who hears it happy. You just have to remember to say it, every day, to those who love you.

And that evening, before falling asleep, each of them said a special thank you: to mommy, to daddy, and even to the sun at the window.