Four-year-old Mason Wegmann was seated at the steering wheel 10 feet off the ground, but he may as well have been on cloud nine.

“He’s huge into construction equipment and construction workers, so for him to get a chance to get on top of the equipment is a big thrill,” said his dad, Brad Wegmann of Marion, who watched his hard-hat wearing son pretend to drive the massive asphalt paver.

Mason and big sister Addison, 5, were able to take the wheel of all manner of big rigs Sunday — a cement mixer, firetruck, semi and helicopter included. In all, more than 20 vehicles were on hand at the Iowa Children’s Museum’s annual “Move It! Dig It! Do It!” in Coralville, a free, day-long event that drew hundreds of families.

Iowa Children’s Museum Executive Director Deb Dunkhase said the event not only lets children get an up-close look at construction and emergency vehicles, organizers also tied in activities focused on the STEM disciplines — science, technology, engineering and mathematics — for the first time this year.

“Everything you see here,” said Dunkhase, “it’s all science and math.”

At one station, for instance, kids learned how to use different types of pulleys to hoist golf-ball-filled buckets, while inside the museum’s theater, other kids constructed a model city from cardboard.

The museum has been hosting the event since 2006, and for many years it required a paid ticket. But Dunkhase said the museum wanted to ensure it was accessible to all kids, so it has shifted to a sponsorship model — with the City of Coralville and Coral Ridge Mall among the biggest contributors in funding, along with the many companies that donate the use of their vehicles.

Dylan Schindler, a worker with American Concrete Pumping, volunteers each year at the event, and on Sunday brought the towering concrete pump to the mall’s parking lot.

“You can’t beat the kids’ reactions,” Schindler said. “It’s pretty rewarding — the kids love it.”

After hopping down from the concrete pumper’s driver seat, 10-year-old James Lippe took a moment to think about what his favorite part of the day had been. “Probably honking the horns,” he decided.

Said his father, David Lippe of Iowa City: “The kids like to check out the vehicles here every year, and they always discover something new.”