In an old cellar that smelled of earth and secrets, little Suzie and her tin friend Droplet found themselves before something amazing. It wasn't a treasure chest or a forgotten toy. It was Grandpa's invention. Suzie focused her eyes, and Droplet lit up his little blue eye. Before them stood a device made of translucent tubes and tanks, where water bubbled quietly. And in that water, without a single clump of soil, cheerful green seedlings were growing.
"Look, Droplet! Tomatoes are growing in water!" Suzie whispered, gently touching a small, still-green sphere with her finger. "And this is basil! I can smell it all the way from here!"
Droplet blinked. "My sensors confirm the presence of plants of the species Solanum lycopersicum and Ocimum basilicum. The system operates on the principle of soilless cultivation. Fascinating."
Suzie laughed. Droplet always spoke so wisely. Together, they admired the water garden. In the upper tank, the tomatoes and herbs were eagerly drinking from the flowing water. In the lower, larger tank, small golden fish were swimming. It looked like a perfect little world.
But then Suzie noticed something. One leaf on a tomato plant wasn't a fresh green. It was somehow tired, a pale yellow. "Droplet, look here," she pointed. "This little plant is sad."
The robot came closer and his sensor scanned the leaf. "Anomaly detected. Lack of vitality. I recommend problem analysis."
"What could it be missing?" Suzie wondered aloud. "Maybe it doesn't have enough water?"
They got to work right away. This was their first attempt. Droplet extended a small tube and measured the water level in the tank. "Water level is optimal. At 98 percent," he announced.
Suzie carefully dipped her finger into the water by the roots. "And the little roots are completely wet. So it's not thirsty." So, the first idea didn't work. But Suzie wasn't upset. "Okay, so we know it has enough water. What's next?"
"Plants require light for growth," Droplet suggested. "Perhaps this special purple lamp above them is weakening."
Suzie looked up. The lamp was shining brightly, bathing the whole room in a soft, magical light. Droplet aimed his little eye at the lamp and examined it for a moment. "Luminous flux is within normal parameters. One hundred percent output. Light is not the problem."
The second attempt was also unsuccessful. The yellow leaf was still just as yellow. Suzie sat down on an old wooden crate and propped her chin in her hand. "So, it has enough water and light. What else could a little plant need? That's everything, isn't it?"
Droplet was silent. His internal computer was processing all the information. Meanwhile, Suzie watched the lower tank. The fish, which had been swimming cheerfully before, were now just slowly drifting about at the bottom. They looked just as tired as the yellow leaf.
"Aha!" Suzie exclaimed. "Droplet, look at the fish! They're sad, too. Do you think it's all connected?"
Droplet focused his sensors on the bottom tank. "Decreased activity in aquatic life forms. There is an 87 percent probability of a connection between the state of the fish and the state of the plants."
"But how?" Suzie wondered. "The plants are up here and the fish are down there. The only thing connecting them is the water."
And then she remembered Grandpa's words, from when he had explained to her how nature works. He had spoken about cycles. About how one thing helps another. She quickly started searching the shelves. And she found it! Grandpa had left a small drawing there, held by a magnet.
On the picture, there was a drawing of a fish with an arrow pointing to a little plant. From the fish, little dots were drawn, traveling up through the water to the plant. And from the plant, another arrow went back down to the fish, pointing to clean water. Underneath, it was written: "Food for fish = food for plants."
Suzie gasped. "I get it now! Droplet, we've been so silly! The fish give the plants food!"
"How is that possible?" asked Droplet, even though his database was already beginning to guess the answer.
"Look," Suzie explained, pointing to the drawing. "The fish eat their food and then out comes... well, you know... what we call poop. And in that poop are nutrients! That's the secret food for the plants! The water carries it up to the roots, the little plants eat it up and grow. And in the process, they clean the water, so the fish have a clean home again."
They understood. The problem wasn't the water or the light. The problem was the food! The fish were hungry because no one had fed them. And when the fish were hungry, they had no way to make nutrients for the tomatoes and basil.
"We have to feed them right away!" Suzie decided.
Luckily, right next to the drawing stood a small container with the label "FISH PELLETS." Suzie opened it carefully and sprinkled a pinch of the tiny pellets into the water.
A miracle happened. The fish seemed to wake up from a deep sleep. One, two, three... they all lunged for the food and nibbled on it cheerfully. In a moment, they were swimming all over the tank again, happy and full of energy.
Suzie and Droplet sat and watched. "Now we have to be patient," Suzie said wisely. "It will take a while for the nutrients to get to the little plants."
Every day, they went to check on their water garden. They wrote their observations in a notebook. Droplet measured the water quality and reported: "Nutrient levels are rising. From zero to five, now to ten units."
And it was true. After three days, Suzie noticed that the yellow leaf was starting to turn green again. And a week later, there was no trace of sadness left. The tomatoes began to turn red and the basil smelled so strong you could smell it all the way out on the street.
Grandpa's birthday was approaching. Suzie and Droplet carefully snipped a few beautiful, deep-red tomatoes and a bunch of fragrant basil. In the kitchen, they washed them and Suzie sliced them into a bowl.
When Grandpa tasted the salad, his eyes lit up. "I haven't eaten such a tasty tomato in years! And this basil! Where did you get it, my little gardeners?"
Suzie smiled proudly. "It wasn't just us, Grandpa. The fish helped too. We learned that in nature, everything is connected to everything else. And that even poop can be very useful."
Grandpa laughed heartily and hugged her. Droplet blinked his little blue eye contentedly. Not only had they saved the garden and prepared the best salad in the world, but they had also uncovered a great secret. The secret of cooperation. And that was tastier than any tomato.
What do you think, children? Will you try planting a cress seed in a flowerpot at home with your parents? You'll see how quickly its green leaves will grow with a little water and light, which you can then put on a slice of bread.