Dropping a chunk of dry ice into an empty orange balloon, Nate Widom predicted that it would explode.
"No, wait," the 10-year-old said yesterday. "It will blow itself up."
After the mouth of the balloon was knotted off, it did just that.
"As the solid heats up, it sublimates and inflates the balloon," explained Joyce A. Trageser, the supervisor of school programs at the Maryland Science Center and the instructor for its first Saturday Morning Science workshop of the year. "Think of it - it's a solid changing to a gas without becoming a liquid. That's pretty amazing."
The trick was one of more than a dozen wow-worthy, hands-on demonstrations in a 90-minute program about "Fire and Ice." The Science Center will rotate through a series of five workshops - though they call them "funshops" - over the next 18 Saturday mornings.
"We want to engage visitors in fun, interactive learning," Trageser said. "Once you start doing the activities, we relate the science to things in everyday life. We hear so much today about kids lacking in scientific and mathematical knowledge. This is a way to relate science to their lives and make it really active."
Other programs in the series explore weather forecasting, where garbage goes, what lies beneath the skin of the human body and the sources of human energy.
With only the Widom family of Leesburg, Va., signed up for yesterday's program, Nate and his 7-year-old sister, Lily, got something of a private science lesson.
Described by his father as "a fifth-grade science nut," Nate couldn't have been happier.
"I want to crank it, I want to crank it. I've got hyper energy here," he said of a manual ice-cream maker that the instructor used to demonstrate changing a liquid mixture of cream, vanilla and sugar into a solid, which they ate at the end of the program.
The kids explored what happens when liquid nitrogen - chilled to a shocking minus-325 degrees Fahrenheit - is poured into a beaker of hot water. "You get a great Hollywood special effect," Trageser explained as a cloud of condensation poured out of the beaker and then disappeared.
They blew bubbles into a deep container with a tub of dry ice in the bottom, shrieking with delight as the bubbles bounced off an invisible layer of carbon dioxide gas and floated back up.
And they gasped as their father, Jeffrey Widom, blew dust through a straw and a piece of tubing toward a lit candle to create an impressive fireball.
The kids also explored the different types of nerve endings in the top sides of their hands, poking a tiny square of skin with paper clips that had been dipped in hot water and ice.
When their grandfather, Barry Klein of Reisterstown, claimed he didn't feel anything during a test designed to provoke pain sensors, Jeffrey Widom remarked, "You're broken. You're not even human."
But Trageser suggested there might be a more scientific reason behind the results.
A 3/4 -inch patch of skin on the back of a person's hand contains 600 pain sensors but only six that detect cold and 36 that distinguish heat, she said.
"I'm very sensitive," Nate said. "I feel all of them - even the barely-est touch."
The instructor asked whether one demonstration - shriveling up a purple balloon with liquid nitrogen in an experiment that looked a bit like the Wicked Witch of the West when she was doused with water - was magic.
Nate responded enthusiastically.
"No. It was science," he said. "But science is magic sometimes."