For the second consecutive Halloween, Halliday Elementary School's gymnasium transformed into a graveyard.

Physical education teacher Ethan Krebs' mask lit up as he instructed his students to face the wall while the ghost hid behind a tombstone, cloaked in the dark. To the sound of spooky music, they crept or ran to the other side of the graveyard, their colored glow-in-the-dark necklaces identifying the ghost in the crowd.

Krebs said the students love the activity.

"It was a great success last year when we did it, and every time they asked me, 'Hey, Mr. K, are we doing Ghost in the Graveyard?' I'm like 'No. That's for Halloween only' ... Last year, we just ended up doubling my session up. I had them run for an hour straight ... and they loved it," he said.

This year, some of his students knew it was coming and dressed accordingly.

"Some of my kids ... specifically wore clothes that glow in the dark ... Some of my kids wore black today because they knew this was going to happen, and they wanted to be sneaky," Krebs said.

In preparation for the activity, Krebs stood up foam mats and covered them in cobwebs, filled the bleachers with the pumpkins students carved Tuesday and lit them up. A projector shines a ghost on the floor, and a laptop plays Halloween music.

"All it is, is a giant game of tag. They like it because I have one person be the ghost ... That's why I gave them five different colors, and the ghost is a different color," he said. "The explorers — whoever is not a ghost — faces the wall so they can't see where the ghost goes and hides. The ghost hides behind the tombstones, which are my mats covered in cobwebs ... When the music starts, the explorers walk through the graveyard. They like it because it's about who's the sneakiest, not who's the fastest."

Once all of the kids either make it to the other side or are tagged out, they begin the next round. The game keeps going until all students are out. When the students are tagged or "scared by the ghost," they stand near their pumpkins.

"They love being out too, because now they get to watch where that ghost is and see where everyone is," Krebs said.

To keep the kids interested, he changes the game a bit by adding more ghosts, or different ones.

The Ghost in the Graveyard game is part of the school's academic carnival, during which kids rotated through various activities including re-engineering and launching the Popsicle catapults they made Tuesday.