Drivers took position. Pit crews stood by. And muscle-powered engines tensed for action, ready to roll.
All eyes were on Reenie Stogsdill, a physical education teacher at Langston Hughes School.
Stogsdill, holding a green flag, gave it a wave.
And with a roar, dozens of fifth-graders' feet thunderously pounded the wooden floor - 497 Speedway was under way.
For the next 20 minutes or so, the school's gym became a squealing, action-packed, student-powered raceway complete with power turns, clever driving strategies and even an occasional wipeout.
"It's a lot of fun," said Jamie Wilson, one of about 30 fifth-graders in the class.
The 497 Speedway - which involves pushing makeshift cars and drivers around gym floors - also was being officiated Tuesday by 40 other gym teachers in nine other Lawrence elementary schools.
Some 800 fourth-, fifth- and sixth-graders are in the race, pushing "cars" each made from an exercise mat placed atop three square-shaped gym scooters.
The race is as much about good health as taking home the prize. Students wear pedometers to keep track of their steps.
"Whoever wins, we get to keep our pedometers," said Nicholas Ebner, catching his breath as a bead of sweat rolled down his face.
Nicholas' team, the Pink Panthers, had a strategy of leaning into the turns, then sitting up for the straightaways.
He held up his pedometer, which showed he already had taken 1,764 steps.
The pedometers were purchased with a $6,000 Kansas Coordinated School Health Program grant, said Lynda Allen, who administers the school district's physical education programs.
Each day this week, from the beginning of the school day to the end, students will wear the pedometers, Allen said.
All of their steps, including the races in the gyms, will be counted. Students in the class with the greatest average steps per student per day will get their own pedometers, Allen said.
Stogsdill said some students had pedometers reading 4,000 to 5,000 steps per day.
"One of the teachers said a student got 10,000 steps today," she said.
Back in the gym, Madeline Chestnut and Katie Davis were taking their turn as the pit crew while two more members of their team, the Hearts, rolled around the cones making up the track.
The girls marked another tally on a sheet taped on the wall as their team rounded another lap.
"It's really fun," Madeline said.
"But it's really tiring," Katie added.