Mira and the Experiment That Failed

Mira was certain that plants liked music.

She had read it somewhere, or maybe heard it on a video, and it made perfect sense to her. People grew happier with music, and so did dogs. Why not bean plants?

For the school science fair she planted six bean seeds in six yoghurt pots. Three went on the windowsill in her bedroom, where she played her favourite songs every afternoon. The other three went on the windowsill in the hallway, where it was quiet.

"The music beans will win," she told her grandfather. "By a lot."

Her grandfather, who had been a science teacher for forty years, only smiled and said, "Let's see what the beans think."

Day ten

On day ten, Mira ran into the kitchen with her measuring ruler and a face like a thundercloud.

"It didn't work!"

The hallway beans were tall and green, with leaves like little open hands. The bedroom beans, the music beans, were short and pale. One hadn't come up at all.

"The quiet beans won," she said, flopping into a chair. "My whole experiment is ruined. I'll have nothing to show at the fair."

Her grandfather put down his newspaper. "Ruined? Mira, this is the most interesting thing that has happened in this house all week."

"It's not interesting. It's wrong."

"It's surprising," he said. "That's different. Wrong means we made a mistake. Surprising means we learned something we didn't expect. Shall we find out which one it is?"

Thinking like a scientist

They sat at the table with a notebook between them.

"First question," said Grandpa. "Were the two windowsills the same in every way except the music?"

Mira opened her mouth to say yes. Then she closed it again.

She thought about her bedroom. The radiator was right under the window, and it was always warm. The curtains were usually half closed because she liked the room dim when she read. The hallway window faced the garden, and the sun came pouring through it every morning.

"No," she said slowly. "My room is hotter. And darker."

"So what might have made the difference?"

"The music… or the heat… or the light." She frowned. "I can't tell which."

"Exactly." Grandpa tapped the notebook. "Scientists call those variables, the things that can change. In a fair test you change only one thing at a time and keep everything else the same. Otherwise you can't be sure what caused the result."

Trying again

Mira did not give up. She planted six new beans, and this time she was careful. All six went on the same sunny windowsill in the hallway, at the same distance from the glass. Every pot got the same amount of water from the same measuring cup at the same time each day.

For music, she put a small speaker next to three of the pots and played songs quietly for one hour every afternoon. The other three sat a long way off down the windowsill in silence.

She measured them every day and wrote the numbers in a table.

By day ten, the beans were almost exactly the same height. Some music beans were a little taller and some quiet beans were a little taller, but there was no clear winner at all.

"So music doesn't do anything?" Mira asked.

"With six beans, in ten days, in our hallway, it didn't make a difference we could measure," Grandpa said. "That's an honest answer. Real scientists would want more plants and more time before they decided anything for certain."

The science fair

At the fair, Mira's table looked different from everyone else's. She had two experiments on it.

At the top of her poster she had written: My First Experiment Failed. Here's What It Taught Me.

She showed the pale bedroom beans and explained the radiator and the curtains. She showed her fair test and her table of measurements. At the bottom she wrote the most important thing she had learned: Change one thing at a time.

The judge, a tall woman with paint on her sleeve, read the whole poster carefully.

"Most people hide the experiment that went wrong," she said. "You put it first. Why?"

Mira thought about it. "Because that's the one that made me think."

She didn't win first prize. She won something her grandfather said was better: a ribbon that read Best Scientific Thinking. She pinned it above her bed, right next to a single, slightly crooked bean plant that was, against all odds, still growing.

---

Try it yourself: Could you design a fair test to find out whether plants grow better in sunlight or shade? Which things would you keep the same?