The Topper Who Only Memorised

On the first Monday of term, a new boy walked into Class 8B carrying a stack of papers so tall that he had to peep around the side of it to find his desk.

“This is Arjun,” said Lakshmi ma’am, their class teacher, adjusting the spectacles that hung from a chain around her neck. “He’s joined us from Pune. Please make him welcome.”

Arjun put the tower down with a thump. “Question papers,” he explained. “The last five years of every subject. With all the answers.”

That Friday, Lakshmi ma’am gave the class a practice test in maths. Arjun finished in twelve minutes and scored a perfect hundred. The next week, he scored a hundred in science. Then a hundred in social studies.

“He’s a genius,” whispered the boy behind Bunny.

Riya wasn’t so sure. “The practice tests are last year’s papers,” she whispered back. “And he has last year’s papers. With the answers.”

Meanwhile, Riya had a secret project of her own.

After Nandi Hills, Bunny’s paper neuron got only four Sundays wrong out of a hundred and fifty. Riya wanted zero. So she started adding clues. Lots of clues.

Did Prakash uncle wear his blue kurta? Was it an even-numbered date? Had Bharath anna’s scooter been washed? Did Happy have dosa or upma for breakfast? Each new clue got its own card, its own string and its own weight. Soon there were forty cards, then fifty, and the living room wall looked like a spider had lost its mind.

And then, one evening, Riya ran the last calculation and shouted, “ZERO! Not a single Sunday wrong! A hundred and fifty out of a hundred and fifty!”

Bunny looked at the wall doubtfully. “Riya, why does the scooter matter?”

“Who cares why? It works!”

Mitthu, who had flown into the strings and was now hanging upside down, said nothing. He was too busy trying to get his foot out of the dosa card.

Then came the first real unit test.

Bunny turned over his question paper. The first question was about the area of a triangle, the same kind as in last year’s paper, but with a garden instead of a flag, and with different numbers. The second was about speed, but the train was going to Mysuru instead of Chennai.

In the front row, Arjun had stopped writing. He read the first question again. And again. He knew the answer to last year’s question by heart: forty-two square centimetres. But this wasn’t last year’s question.

When the results came back, Arjun had scored thirty-eight. He sat very still and looked at the paper for a long time.

Lakshmi ma’am didn’t scold him. After class, she sat down next to him. “Arjun, you are a very hard worker,” she said gently. “But you learned the answers, not the way to get them. A practice paper you have already seen can’t tell either of us what you really know. That’s why the real exam always has new questions.”

That same month, Riya’s super neuron faced its own exam: six brand-new Sundays that weren’t in Prakash uncle’s notebook when she built it.

It got four of them wrong.

It said “play” on a Sunday of pouring rain, because Prakash uncle happened to be wearing his blue kurta, and in the old notebook, blue-kurta Sundays had always been sunny. It said “no match” on a perfect blue morning, because Happy had eaten upma.

Bunny’s simple neuron, with just five sensible clues, got five of the six right.

Riya stared at the numbers. “Mine was perfect,” she said quietly. “How can perfect be worse?”

Bunny thought of Arjun’s tower of papers. “Because yours wasn’t learning about cricket weather,” he said slowly. “It was learning those hundred and fifty Sundays by heart. Even the accidents. Like the kurta.”

The next day, Riya and Bunny told Lakshmi ma’am the whole story. She smiled, picked up a piece of chalk, and drew a scatter of dots on the board.

“Here are some examples,” she said. “A model’s job is to draw a rule through them, so that when a new dot comes along, the rule can guess where it goes.”

She drew a flat straight line that missed most of the dots. “Too simple. This rule doesn’t even fit the examples it was given. That’s called underfitting.”

Then she drew a crazy wiggly line that twisted up and down to touch every single dot. “Too complicated. It fits every old dot perfectly, but look how it swings wildly in between. A new dot here, or here, and it’s badly wrong. That’s overfitting. It has memorised the examples, noise and accidents and all.”

Finally, she drew a smooth, gentle curve that passed close to most of the dots without touching all of them. “Just right. It has learned the pattern, not the dots. Scientists call that generalising.”

That evening, Bunny invited Arjun home. Arjun brought his tower of papers, and looked at them sadly.

“In my old school,” he said, “everyone called me a rattu tota. A parrot who only repeats what he has heard.”

From the balcony railing came a furious squawk. Mitthu puffed out every feather he had.

“Excuse me,” he said. “I am a parrot. And I will have you know that parrots are extremely intelligent birds.” He paused. “Although,” he admitted, “when I was young, I did once learn the whole of Dadi’s grocery list by heart. Every week I would shout ‘two kilos onions, one kilo dal!’, even when the onions were already in the kitchen.”

Arjun laughed for the first time that week.

“Memorising isn’t bad,” said Bunny. “You have to remember things to learn them. But then you have to understand why, so you can use it on something new.”

“Then teach me the why,” said Arjun. “And I’ll teach you something. My cousin in Pune works with AI. She says they never test a model on the examples it learned from. They hide some of the examples away first, and only use them at the very end. Like a sealed exam paper.”

So that’s what they did. Riya took Prakash uncle’s notebook and covered thirty of the hundred and fifty Sundays with paper, then sealed them in an envelope. “Nobody looks at these,” she said, “until the very end.”

They trained on the other hundred and twenty. Every time Riya wanted to add a new clue, they tested it, and only kept it if it helped on Sundays it hadn’t seen. The blue kurta went. The scooter went. The dosa card went, to Happy’s great disappointment.

When they finally opened the envelope, the neuron got twenty-eight of the thirty sealed Sundays right.

“Ninety-three percent,” said Riya, a little proudly, “on Sundays it had never seen. That’s a real score.”

And three weeks later, in the next unit test, Arjun got seventy-nine. Not a hundred. But every single mark was his own.

Mitthu, who had been listening from the top of a pile of books, nodded wisely. “Two kilos onions,” he muttered to himself, “only if there are no onions in the kitchen.”