Water in the Same Container.

At the next science practice, Saeon went to the low observation bench. The two containers they had seen from the hallway stood side by side. Sodam and Dure followed along the same floor.

Saeon looked at the notebook in Dure's arms. Two round marks had filled it at the math station. What would continue on today's page?

Teacher Gwak Doeun stood beside the bench. The wide hallway behind them was open. Saeon stopped in front of the containers.

Both containers were clear plastic. Their sandy-colored lids were locked, and they stood in low bases. Ice filled the left container. Water was visible in the right.

The ice held up bumpy corners. The water spread low across the right container's bottom. Saeon pointed between them.

“We're comparing these two now.”

The teacher pointed to the left container.

“This one was prepared separately for observing.”

The hand moved toward the right base.

“Today's record is this container, before and after. Don't join the two containers into one record.”

Saeon pulled back the hand reaching left. Similar containers did not mean they could connect them. An earlier picture sat beside the right container.

The picture showed the same sandy-colored lid. Inside was ice made from water. In the real container now, no lump of ice remained.

“All the ice in the earlier picture melted. The container wasn't opened.”

The teacher lowered a hand from the base.

“Nothing was put in or taken out, either. Connect the record.”

There were two observation boards, too. The left held the right container's earlier record. The right had places for before-and-after pictures and their explanations.

Two picture spaces waited on the right board. Above them, small words read “Before” and “After.” The spaces for explanations below were empty, too.

Another picture lay on the shelf, showing the container now. Water inside, without ice. Saeon picked that one up first.

The clear water was drawn wide and easy to see. Saeon placed that picture in Before, then slid the ice picture into the remaining After space.

“Water first. It's easy to see.”

Dure paused while opening the honey-colored notebook. Sodam looked at the little words above the pictures. Saeon pulled back their hands and studied the whole board.

Water first. Ice afterward. But today's container held only water. The pictures looked neat, yet the record ran backward.

“Hang on. Before means before it melted.”

Sodam pointed to the empty shelf beside where the earlier picture had been. Saeon picked up the ice picture again. Ice in Before. Water in After.

“I switched them. Now they connect.”

A temporary explanation lit up below the pictures.

Saeon studied the water in the after picture. This time, they did not mistake it for an empty container. Saeon had not missed the water left inside.

Ice had corners. Water lay flat. The pictures had different names, too. Since ice had become water, perhaps “a different substance” was right.

“The shape changed. It became something different, right?”

Dure looked between the names below the pictures, too. They drew a short line down the notebook's middle, dividing before and after into different substances.

“Different names. I'll write them separately.”

Saeon raised a hand toward the after explanation. Smooth amber light circled beneath the tidy words. It looked like a record already finished correctly.

A round light knot sat on the left board's edge. Cream-colored, eye-like gaps showed between cloudy amber strands. The strands continued to the explanation's border on the right board.

One Tangle wrapped around both boards. On the right, its strands had hardened flat. Even seeing the smooth coating, Saeon did not lower their hand yet.

It was a device made from a mistaken idea. It did not wrap around the containers or touch the water. While they waited, it did not spread beyond the boards.

Saeon stopped just before pressing the explanation space. The before-and-after pictures were in order now. But did different names mean different substances?

What had the ice been made from?

Dure raised an empty hand in front of their chest.

“Not yet. Hear me out, too.”

Saeon lowered the hand outside the board, moving back more slowly than when shifting the pictures. Dure's fingertip went to the earlier picture.

“I'll start here.”

Dure pointed to an ice corner, then held a finger in front of the water at the right container's bottom. Saeon checked both places the hand had passed.

“The ice was made from water.”

Dure glanced at the temporary explanation. Their lips closed, then they turned back to the picture.

“We need to look at the water left, too.”

Saeon looked between the earlier picture and the real container. The solid shape was gone. Still, they could follow from the picture to the water remaining inside.

Sodam adjusted the arm of their glasses. From outside, they pointed to the right container's locked lid.

“Two conditions.”

The fingertip moved between the earlier picture and the container now.

“A record of the same container. Nothing put in or taken out.”

Saeon looked at the separately prepared left container. Its ice was still there. The earlier appearance of today's melted ice belonged in the record, not in that other container.

“So we connect just these two.”

Saeon pointed below the before and after pictures. The knot twitched slightly. A thin cream-colored pin reached from Sodam's fingertip to the board's border.

A crack opened in the smooth amber coating. The words “a different substance” remained below. Saeon looked from the words to Dure's hand.

Dure kept a blank page open in the notebook. On the left, they drew a lump with corners. On the right, they drew water spread across a container's bottom.

Around each drawing, Dure added the outline of the same container. Saeon watched the line continue up to the lid. No blank space broke the connection between ice and water.

“Before, it was solid.”

Dure's fingertip paused at the left picture, then moved right.

“Now it's liquid.”

Saeon looked at the explanation spaces below. There were separate places for what it was and what state it was in. Before, Saeon had seen a changed shape and changed both answers together.

Dure wrote “water” below the before picture. Under the after picture, they wrote the same word. A fingertip slowly connected the two.

Dure erased the line down the middle, then pointed again to “water” below the drawings.

“I split them just by their names.”

Dure's hand moved from before to after.

“Even melted, it's the same water.”

Dure looked up at Saeon.

“What changed was its state.”

Saeon checked the right container again. No new substance had entered it. The ice in the earlier record had melted and remained as liquid water.

“I changed it just because of the shape.”

Saeon erased the temporary after explanation. They wrote “water,” then “liquid” below it. This time, they filled the two blanks separately.

“Same water. Now it's liquid.”

Dure pointed to both pictures again. Ice in Before. Water in After. The same container, in the right time order.

The fingertip paused first on “water,” then on “liquid.”

“What remains and its state. Both right.”

Dure swept a hand once along the notebook page's edge.

“This is where we finish.”

The knot on the boards' borders loosened. The smooth coating unwound into long strands, too. Turning cream-colored, the strands lay straight on the boards.

Saeon looked from board to container. The right container still held liquid water. The ice in the separate left container had not turned into light, either.

The little result light at the front edge came on. Saeon showed the teacher the corrected explanation.

“The ice was water, too. I said it was different just because of the shape.”

Dure supported the notebook with a palm.

“The ice melted into liquid water. It's the same substance.”

The teacher waited until Dure finished, then nodded.

“Nice and clear.”

The ice had melted, changing from solid to liquid. That change was called melting. Saeon remembered Dure's words again: the same water.

A little recess at the front of the base opened. Saeon kept hands off the container and leaned forward. Inside lay a real three-step stone stair piece.

The slot above the highest step was empty. No letters. No patterns.

Blue light climbed the step edges. Last science practice, it had reached just below the upper slot. This time, it reached the rim and pooled there.

Saeon started to look for light reflected in the water, then turned back to the recess. The light pooled in the stone's empty space. The water remained separately in its container on the base.

“It reached the edge.”

None of them took the piece out. Saeon's hands stayed outside the recess, too. After a moment, it closed.

Dure tilted the notebook slightly toward Saeon. Before: ice with corners. After: water spread low. Under both pictures, the word “water” remained side by side.

Saeon started following the space between them with a fingertip, then stopped. Without touching the book, they looked all the way to the end. Dure showed the final picture, then closed it.

“Got the before-and-after record.”

Sodam turned toward the open hallway. Saeon stepped back from the bench, too. Today, even the name of the water left behind was recorded correctly.

All three walked along the same lowest floor. Saeon stood beside Dure and the hugged notebook. They kept remembering the light resting at the empty slot's rim.

What was at the top?