As Jack Walsh wrapped up a joke about gummy bears turning to polar bears once submerged in liquid nitrogen, there was a loud bang, followed by an eruption of children’s laughter.

“We just proved that liquid nitrogen cannot only inflate a balloon, it can blow up a balloon,” said Walsh, the owner of Sub Zero, an ice cream shop in Federal Way that uses liquid nitrogen to make ice cream.

Minutes prior to the explosion, 40 fifth-graders at Lakeland Elementary watched Walsh pour liquid nitrogen in a plastic bottle and put a balloon over the top.

They had just learned that nitrogen expands 692 times in gas form.

Walsh’s visit to Lakeland Elementary last Friday was one of many visits to schools planned for this year. Already, he’s been to Kilo Middle School and Lakegrove Elementary.

And it’s not just local schools he visits. His scientific experiments in schools started five years ago and, in that time, he’s gone as far north as Mount Vernon. In April he plans to go as far south as Eatonville.

“Every year it’s increased in number,” Walsh said. “I’m probably at 50 schools a year.”

Walsh’s experiments have young minds thinking of the boiling point for water (212 degrees Fahrenheit) and the boiling point for nitrogen (-321 degrees Fahrenheit). They learn about the “Leidenfrost effect,” a phenomenon that allows Walsh’s hand to quickly touch liquid nitrogen without getting burned – or worse, falling off.

The visits get students excited about science, even without the promise of a ice cream at the end.

“It keeps them active,” said Lakeland Elementary teacher Amanda Werner. “It keeps the kids involved.”

Werner teaches highly capable students in third, fourth and fifth grade, and she typically applies a “real-world” approach to her teaching.

“I wanted them to understand, ‘Here’s what we’re learning, but this is why,'” she said. “I always try to give them a real-world component.”

Werner had been to Sub Zero before and had seen how liquid nitrogen turned cream, milk and sugar into ice cream.

“[I] thought this would be a really good culminating project for my class, because they already had the unit and a prequel to the other two classes for them to understand the scientific method, which helps K all the way up to 12, and then the other part of it is space of matter, which is a third-grade unit, so it should be something they continually touch upon,” she said, adding that Walsh’s presentation would also allow for students to engage with their parents by bringing them into Sub Zero.

Walsh said that while kids like his experiments, his experience is that adults sometimes like them even more.

“It appeals to all ages and, for more people, they learn things from it, and it’s both educational and entertaining for everyone,” he said.

Entertaining, like when Walsh tells a story about Hall of Fame baseball player Ted Williams’ request to freeze his head after he died, or of his own story on how he became interested in science.

“When I was 11 years old, NASA sent the first man to the moon,” he told the students. “I was your age, and all of us were watching TV, watching that first step.”

NASA also went to Walsh’s school and gave a presentation similar to the one he gave students.

“Some of the things they showed me, I still remember now more than 45 years later,” he said. “I get to do some of the same things NASA did, but I don’t get to go to the moon. But we’re going to have better ice cream than what they ever had.”

After several other experiments that included inverting a bottle filled with liquid nitrogen and water to see which liquid was heavier, and one watching what would happen when a flower was instantly frozen, ice cream was served.

“I love science, and this is a way I’m able to share my love of science with kids and get them excited about science and hopefully walk away knowing a few scientific principals,” Walsh said.

Fore more information about Sub Zero ice cream and how to get students involved, visit www.subzeroicecream.com/education