My Thought First.

At the next math practice, Saeon went to the gallery. Dure walked alongside, carrying the honey-colored notebook. Sodam looked ahead at the table under the arch.

At the last science bench, Dure had erased a line. It had divided the ice from the water. Saeon remembered the explanation Dure had changed. This time, Saeon wanted to hear it from the start.

The navy stone table came into view, with its eight corners. All three silver trays were empty. The blue cores had been put away.

The three little lamps around the edge were dark. Two silver clock disks sat side by side in the middle. The rounded tips of their hands showed above low covers.

Dure opened the notebook on the shelf. Two round dents remained from the last math activity. Saeon looked at those marks, then at the disks.

They hadn't read today's record yet. They couldn't just bring back the two full turns from last time.

Teacher Gwak stood beside the table. The wide hallway stayed open behind the three friends.

“The setup is finished. Find the matching record.”

Saeon read the two parts separately. One minute. Thirty seconds. They weren't supposed to finish setting something up now. They had to write an already finished time in another unit.

Sodam adjusted the glasses.

“Hang on. Check the units, too.”

Saeon's eyes passed between minutes and seconds. Seconds was the word they needed to keep. Maybe the numbers in front could just go together.

Saeon opened the triangular folding board. On a blank side, Saeon wrote 1 first. Then 30 right beside it, followed by seconds.

“Just stick them together, right?”

The board read 130 seconds. Saeon placed it below the record display. The one and the thirty were both there. That seemed to include everything.

Sodam studied the original record instead of the board. A fingertip stopped at the word minute. Dure copied only 1 minute onto a blank notebook page.

“Change the minutes, and that's it?”

The thirty seconds hadn't made it onto the page. Saeon looked at the empty space after Dure's words.

Dure pointed toward the left disk. Their lips parted a little, then closed. The hand stopped just outside the disk.

Saeon had been about to pick up the board. Now Saeon watched that hand, ready to wait for the full explanation. But this time, there was room to wait before the words even started.

Dure raised an empty hand to chest height.

“I'll say my thought first.”

Saeon let go of the folding board. No new number had been written yet.

“You start.”

Amber strands wrapped around the sides of both disks. The dull strands joined in a round knot. Two cream-colored gaps showed between them, like eyes.

Inside the right side lay a smooth, flattened layer. Its shine looked like the one beside two hundred seconds last time. Saeon peered behind the neat outer surface.

It was a device made from a mistaken idea. One Tangle wrapped only the two disks. Its strands didn't reach toward the children or block the hall.

Saeon looked at the 130 seconds on the board. The word minute had been dropped, and the numbers pushed together. Nobody had checked whether the hands moved for that much time.

Did erasing a word change the time, too?

Dure moved the blank notebook page closer to the table. Saeon slid the folding board aside. Now there was room for Dure's hand.

A shallow recess opened at the front of the table. Saeon bent down, keeping both hands outside. A tiny stone staircase with three steps lay inside.

The hollow above the top step held no stone. A little stone remained separate below the empty space underneath. Last time, light had risen from below here.

This time, blue light flowed from top to bottom. It followed the step edges until it touched the little stone. Then, slowly, it climbed back along the same path.

The stones stayed still. Only the light moved back and forth. It wasn't blinking on and off. Its flow slowly changed direction, like a long breath in and out.

“It's coming back this time.”

Sodam pointed from outside the recess. Saeon watched the whole journey both ways. At the science bench, light had pooled around the top hollow. Here, it reached the lower stone, then returned.

No letters or patterns appeared. Nobody reached in to take the piece. When the recess closed, Saeon straightened.

The teacher lifted the low covers from the disks. Shallow, rounded grooves ran around each edge. Both hands rested at their own starting groove.

Saeon read the thirty seconds on the right again. The second part wasn't another minute, as it had been last time. It was the rest of the same setup time.

Dure pointed beside the left starting groove.

“I'll try turning this one first.”

A fingertip pressed the playback control at the table's edge. The left hand moved to the next groove. The right hand stayed at the start.

The amber knot gave a small twitch in place. Dure pulled back and watched the hand. Saeon counted along beside it.

There were six sections of ten grooves around the edge. Every groove was the same distance from the next. Ten clicks sounded as the hand passed one section.

Twenty. Thirty. The left hand passed the opposite side. Hearing thirty, Saeon almost raised a hand. But the part moving now was the first minute.

Saeon lowered that hand outside the table. Dure's starting spot came into view again. The clock hand hadn't returned there yet.

Forty. Fifty. The last section had the same spacing, too. After the sixtieth move, the hand reached its first groove.

Dure looked up.

“One full turn is sixty seconds.”

The words stopped there for a moment. Saeon didn't say the next number for Dure. Dure's fingertip still rested beside the left disk.

“I checked the minute. I'll check the rest next.”

Saeon looked at the notebook page. There wasn't a final answer yet. But there was a stretch of time they had checked. This was different from Dure saying everything at once.

Sodam pointed to minute in the setup record, then seconds in the instructions.

“We're changing one minute. We saw it in that turn.”

The fingertip stopped beside the left disk.

“Sixty seconds. Not a hundred.”

A thin cream-colored pin touched the strands at the side. The smooth inner layer stopped moving. Silver showed through the strands beneath it.

“Same rule for both. Keep the seconds at the end, too.”

Soon the right hand began to move. The left stayed where it had returned. The two times weren't starting together and being counted on top of each other.

Saeon counted again from the right hand's first move. It passed ten grooves, then another ten. Dure's fingertip stayed out of its path.

At the end of the third section, the little clicks stopped. The right hand stood opposite its starting place. It hadn't gone all the way around.

Dure pointed to the right disk.

“Thirty moves here. Thirty seconds.”

On the blank page, Dure wrote the left disk's sixty seconds. Beside it went the right disk's thirty seconds. A fingertip joined the two written parts.

“Include the leftover seconds. Then we're done.”

Dure's finger traveled from one minute to thirty seconds in the record.

“Sixty seconds first. Add the thirty seconds after that.”

Now Saeon opened the folding board again. A hand paused beside 130. Sixty hadn't been there when Saeon joined one and thirty. But it had been there on the disk.

“Sixty plus thirty. Ninety seconds.”

Dure looked at the two numbers in the notebook.

“I only wrote the minute at first. It takes the rest, too, to make ninety seconds.”

Dure swept a fingertip once along the page. It reached the end, and Dure looked up. Only after Dure finished speaking did Saeon erase the board's number.

“I only took out a word. I needed to change the minute to seconds first.”

Saeon wrote 90 seconds. Sodam pointed to the board beside the original record.

“One minute thirty seconds. The same time.”

They had changed the first minute to sixty seconds. They hadn't left out the thirty seconds after it. Everything from the start of the record to the end was there.

The minutes and seconds showed the same amount of time. Saeon took sixty away from ninety in their head. Thirty remained. Split into parts again, it still matched the original record.

The strands left on both disks loosened. The outer knot and shiny inner layer unraveled together. Cream-colored specks scattered. The disks stayed right where they were.

All three lamps around the edge shone clear cream. Saeon showed the corrected board to the teacher.

Dure looked from the display to the notebook. A hand rested on the written sixty. That line had come before Dure had checked the rest.

Saeon spoke.

“We weren't supposed to stick the numbers together. We changed how we wrote the same time.”

Dure held up the notebook, too.

“I tried the minute first. Then I checked the thirty seconds after it.”

The teacher waited until all three had finished speaking, then nodded.

“Nice and clear.”

Dure shut the notebook and hugged it close. Saeon folded the board, too. Dure's words before they had a finished answer stayed in Saeon's mind.

“I liked hearing your thought first.”

Dure opened the hand under the notebook a little.

“I don't have to wait until I can say it all.”

Sodam headed toward the open hall. Beyond the next math arch, Saeon could see boards divided into parts. Saeon glanced that way, then came alongside Dure.

All three were still on the bottom floor. Saeon remembered the light reaching the little stone, then coming back. Beyond the stairs, the upper reaches were still out of sight.

What was at the top?