One hot summer day, turtle Bertha was sunbathing on her favorite rock by the pond. The sun was blazing so intensely that even the insects were hiding in the shade.
"Oof, what heat," sighed Bertha. "I can feel my shell burning. I wonder if it's warmer from the sun or from this scorching rock."
Bertha was a very curious turtle. "I must measure this!" she decided. "But how?"
She climbed down from the rock and slowly made her way to the grove where her friend hedgehog Philip lived. Philip was the cleverest of all the little animals.
"Hello, Philip!" called Bertha.
Philip poked out his snout. "Bertha! What brings you on such a hot day? Shouldn't you be resting somewhere in the shade?"
"I have a scientific mystery," explained Bertha. "I want to find out whether my shell is heated more by the sun shining from above, or by the hot rock under my belly."
"Hmm," Philip pondered. "That's an interesting question. We need some way to measure temperature."
The animals set out together to explore the area around the lake. At the edge of the sandy beach, they found a forgotten young scientist toy set.
"Look, Bertha!" exclaimed Philip excitedly. "There's a small thermometer, a magnifying glass, and even a notebook with a pencil!"
"First we need to think about how we'll measure," said Philip. "We need to measure the temperature of your shell when you're sitting on the rock, and then when you're just in the sun without touching the hot surface."
At that moment, butterfly Mark flew over. "Hello, friends! Can I help you?" he offered. "I can call my butterfly friends. Together we could lift Bertha."
"That's a great idea!" exclaimed Philip.
"So, let's begin measuring," said Philip. "First we'll find the air temperature in the shade." He placed the thermometer in the shade. "Twenty-six degrees Celsius."
"Now please sit on that favorite rock of yours in the sun and stay there for exactly ten minutes," Philip requested.
Bertha obediently waited. The sun blazed on her shell and heat from the rock penetrated her belly. Meanwhile, Philip prepared a small platform from branches with the butterflies.
"Time's up," announced Philip and carefully placed the thermometer against Bertha's shell. "Thirty-four degrees Celsius! That's eight degrees more than the air temperature."
"Now the second part," said Philip. "Butterflies, could you please carry Bertha to our platform?"
The butterflies gathered around Bertha, lifted her into the air with their combined strength, and carefully placed her on the platform of branches.
"Now we'll wait ten minutes again," said Philip.
After ten minutes, he measured the temperature of Bertha's shell again. "Thirty degrees Celsius!" he announced.
"So the difference is four degrees," pondered Mark.
"That means both the rock and the sun are heating my shell!" concluded Bertha excitedly. "And it seems each of them contributes about equally – four degrees each!"
"Exactly," nodded Philip. "The sun heats from above and the rock from below, and together you feel eight degrees more than the air temperature in the shade."
Bertha was thrilled with her discovery. "And one more thing," she added thoughtfully, "when I'm on the rock, I'm heated from above and below. That's why I feel warmest there. But when I want to cool down, I have to go into the shade and also onto something that isn't hot, like grass."
"Excellent, Bertha! Now you better understand how heat works," Philip praised her.
Bertha was very proud of herself. "Tomorrow we could measure whether the water is warmer in the shallow part of the lake or in the deep part," she suggested.
"That's a great idea for another experiment!" smiled Philip.
As the animals were parting ways, Bertha stopped once more at her rock. "Thank you, rock, for helping me stay warm. Now I know why I love you so much," she said and slowly walked away to her little home, where she wrote down all of today's discoveries.
And when the sun rose the next morning, Bertha already had a new plan ready. Because she knew that the best way to understand the world is to ask questions and seek answers to them.