A story to share together
The Beans in the Plane Tree's Shadow
When Elif and Can's beans under the plane tree become stunted, Can tries to rescue them with plenty of water, but the soil turns to mud. By measuring the shade, setting up a dark cupboard experiment, and reweighing the potted soil weeks later, the two friends discover that plants build themselves from air, water, and light.
Page 1
Elif and Can volunteered to bring two empty wooden garden beds in the schoolyard to life. One of the beds was out in the open sun, while the other sat in the wide shade of an old plane tree. The two friends buried ten bean seeds in each bed and gave the soil a thorough watering. A week later, all twenty seeds had sprouted and poked their heads out of the soil. Can was already daydreaming about carrying a basket full of fresh green beans into the classroom at harvest time.
Page 2
Two weeks later, the seedlings in the sun stood fifteen centimeters tall, deep green, and straight as arrows. The ten seedlings under the plane tree, on the other hand, were only five centimeters; they were both pale and frail. "They must be thirsty," Can said, and that week he watered the shaded bed with bucket after bucket every single day. Before long, the soil turned into squishy mud, and the bottom leaves of two seedlings started turning yellow. When Elif pressed her finger into the muddy soil, she realized the roots couldn't breathe in the waterlogged ground.
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Elif suspected that the real problem wasn't a lack of water, but a lack of light. Every recess throughout the week, she went out to the garden and recorded where the plane tree's shadow fell across the beds in her small notebook. Adding up her notes, she found that the open bed received about seven hours of direct sunlight each day. The bed under the plane tree, however, got only three hours of sun. The seedlings in the sun had soaked up more than twice as much light, and they were three times taller than the ones in the shade.
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Can then asked the question that had been puzzling him: "Do plants eat soil to grow?" To find out, they set up two separate experiments by the classroom window. First, they dried a pot of soil in the sun and weighed it on a balance scale; the soil weighed exactly three thousand grams. They planted a single bean seed in this pot. Then, taking two bean seedlings that had sprouted on the same day and were the exact same height, they placed one inside the classroom's dark cupboard and shut the door tight, leaving the other by the window.
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A week later, Elif eagerly opened the cupboard door. The seedling kept in the dark had stretched taller than the one by the window, but it was thin and floppy, and its leaves were completely yellow. The seedling on the windowsill was short, sturdy, and bright green. "It stretched out trying to reach the light by using up the food stored inside its seed," Elif said quietly as she set the two seedlings side by side. "That means the leaves need light to make new food, not mud or extra water."
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So, what did the leaves make food with? In the science lab, Can painted clear nail polish onto the underside of a bean leaf, and once it dried, peeled the thin film off with tape and placed it under a microscope. Peering through the lens, he spotted hundreds of tiny pores that looked like little lips. Elif remembered that carbon dioxide from the air enters the leaf through these pores, and oxygen exits through them too. Powered by the energy of sunlight, the leaf turns carbon dioxide and water from the roots into sugar, using that sugar to grow.
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Now they knew exactly what the shaded seedlings needed. Carefully digging up the ten seedlings under the plane tree along with their roots, they transplanted them to the sunny bed. That gave them twenty bean plants in the sunny bed, and they set up a reed stake beside each one to climb. In the shaded bed, they planted spinach and parsley seedlings, which could manage with very little sun. This time, Can didn't dump water by the bucket; he first poked his finger into the soil to check how dry it really was.
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Four weeks later, they gently removed the bean plant from the pot with the weighed soil, shaking every grain of dirt from its roots back into the pot. They dried the soil for three days and weighed it again; the scale balanced once more at exactly three thousand grams. The bean plant alone weighed thirty-six grams. After letting the plant sit by the window until it dried to a crisp and rustled, its weight dropped to just four grams. That meant thirty-two of the thirty-six grams—eight-ninths of the whole plant—had been water.
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So where had the remaining four grams of dry matter come from, given that the weight of the soil hadn't changed at all? Elif and Can thought back to the pores they had seen under the microscope and put the pieces together. The plant's dry weight was formed almost entirely from carbon dioxide taken from the air and water drawn by the roots, joined together by the energy of light. The tiny amount of minerals from the soil was so small the scale couldn't even detect it. Holding the dried plant in her palm, Elif smiled in amazement, realizing that most of it was built from air and water.
Page 10
When they returned to the garden a few weeks later, the beans had climbed halfway up the stakes, and the first white flowers were blooming among the leaves. Under the plane tree, the spinach leaves had broadened, and the parsley had grown into a lush green bundle. Elif gently turned over a spinach leaf to look curiously at its underside, where the hidden pores were. Can grabbed a magnifying glass from the classroom and squatted down beside her. Together, the two friends spent a long time watching the flecks of light drift across the leaves swaying in the gentle breeze.
