It was only when she saw them gathered at the far end of the school yard, talking solemnly among themselves, that she realized what it was. None of them had laughed all day. None of them had smiled.

She got up from her seat and walked to the window, eating an apple. She hoped they weren’t catching anything. It was the class outing to Lake Berryessa on Monday, and she didn’t want to have it spoiled by colds or flu.

She was curious to see what the children were doing. Normally, they ran around the yard, playing tag or ball. But today they were standing in a circle, all by themselves, and they had linked arms. They were circling around and around, their feet shuffling as if they were dancing. She had never seen children do anything like that before, and she found it strangely upsetting.

A gray cloud crossed the sun, and the school yard went dull. But the children continued to shuffle and sway, and she was sure she could hear them singing.

At that moment, Mr. Saperstein, the visiting music teacher, came in through the school porch and waved a hand to Mrs. Novato in greeting. He was wearing his frayed Panama hat and his frayed linen suit, and he had a camera slung over one shoulder and a flute case over the other.

“Hello, Mrs. Novato. How are you getting along? Doesn’t the weather get worse every year? It’s the Russians and their magnetic fields. We should tell them to stop or pay the price.”

Mrs. Novato was frowning as she stared at the children, and she didn’t answer. Out in the hall, Mr. Saperstein paused, and then came into her classroom and said, “What’s so fascinating? I could have walked in naked.”

Mrs. Novato looked at him quickly and smiled. “Oh, I’m sorry. I was just fascinated by what my class is doing.”

Mr. Saperstein raised his spectacles and squinted out into the dull sunlight.

“They’re dancing, aren’t they?” he said. “What’s so strange about that?”

“It might not have been strange in the days of square dances and folk festivals,” said Mrs. Novato, “but these children have never danced like that before in their whole lives. They don’t know how.”

Mr. Saperstein shrugged. “They obviously do, or they wouldn’t be doing it. It’s interesting, though. It looks like a Greek folk dance. The way they’re all holding on to each other’s shoulders and jogging around like that.”

He took his camera off his shoulder, made some fussy adjustments for the distance and the light, and then took three pictures of the children as they hopped and danced around.