From tabletop CD and styrofoam tray hovercrafts to life-sized ones students can ride, Explo introduces the science and fun of hovercrafts to over 500 students at the Wellesley Science & Tech Expo.

"We've been looking for you everywhere!" One mother, smartphone camera at the ready to photograph her son as soon as he crouches down on the hovercraft's hull, is excited. She and her family had been combing the building — Wellesley High School — asking every volunteer in an orange shirt where they could find us. After hitting all three floors, sometimes twice, they spotted the Explo sign and came inside.

"When my son saw in the program that he could ride hovercrafts," she says, "his eyes just went wide! So we knew we had come find you. Look, he loves it!"

Andy Smith, Curriculum Developer at Explo, and Kristi Jacobi, Explo's Assistant Director of Curriculum and Instruction, take turns pushing the hovercraft he's riding up and down the course, his giant smile giving his eyes a run for their money. Next to him, a line of students watching the hovercraft in action and waiting for their turn to ride snakes out the classroom door, and won't let up for the next four hours.

We are at the Wellesley Science & Tech Expo, an "interactive science museum" where children (and their parents) from all over greater Boston can come and explore the hands-on world of science, tech, math, and engineering in the form of interactive, project-based experiments and exhibits. And in rooms 227 and 229, we're busy introducing students to the physics (and magic) of hovercrafts in motion.

Build Your Own Hovercraft!
Download our hovercraft plans. All the materials you need are available at your local hardware store (except maybe the meat tray — we got that at a grocery store). Our hovercrafts are customized with racing stripes and flames, but we'd love to see how you customize yours! Post a picture of your hovercraft on our Facebook page. Happy building!

"Does anyone know what makes a hovercraft hover, instead of flying like a plane?" Laura Farmer, Curriculum Developer at Explo, asks a throng of students. The students, ranging in age from elementary school to early high school, crowd around a table covered in CDs with sports bottle caps glued over the center holes, orange Explo balloons, and bicycle pumps.

"It doesn't use that much power," one of the students responds.

"That's true," Laura says, "A hovercraft uses a pocket of air like a pillow, and the hovercraft floats on that pillow." To make this first version of a hovercraft — one of three we're demostrating — students pick up a balloon, pump air into it until it's ready to burst, then twist the end and pull it over the mouth of a closed bottle cap.

"If I inflate the balloon more, will it go higher?" a students asks. "Not higher..." Laura says. The student's eyes light up once he figures out the answer. "It'll go farther!"

At the next table, where Barb Trainor, Explo's Director of Curriculum and Instruction, is asking students the difference between sliding on a wood floor in their shoes versus their socks.

"Your feet get stuck when you're wearing sneakers," a student says. "You can't go anywhere."

"That's right," Barb says. "That's called friction." Taking a CD hovercraft in hand, Barb demonstrates how to eliminate friction and create that much-needed cushion of air.

"Place the CDs on the table and squeeze the bottom of the bottle cap," Barb says. "Now, pull up on the top, and push your hovercraft across the table."

CD hovercrafts, propelled by air seeping out of the balloons and through the bottle opening, skitter across the tabletop, transforming it from a standard wood surface into a DIY air hockey ring. "Cool!" one student says. Turning around, he plucks up his hovercraft and beelines over to a new set of hovercrafts, built out of styrofoam trays, mini motors, and spinning propellers, gliding up down a long pair of parallel tracks.

Come Ride a Hovercraft!
On Sunday, April 13, 2014 we're hosting the Explo Learning Festival — an afternoon of fun, discovery, and exploration — on the campus of Wheaton College for students ages 6 to 12. Build a hovercraft, then ride on one, too!

"So who can tell me which way the air is going?" Brent Ruter, Head of Programs at Explo at Yale, says. "Feel the air on either side of the fan. Which way is it coming out?"

"That way!" a student answers, pointing in the right direction.

Holding up the hovercraft at the students' eye level, Brent turns it propeller-side toward them, and asks, "So where is it going?"

"Through the hole!"

"Yes!" Brent says. "That's how this hovercraft works. The propeller pushes the air through the hole and underneath the hovercraft, making it float."

Figuring out how the air escapes (from under the tray) and how the hovercraft manages to keep moving forward (the right balance of the weight of the motor and the propulsion of the propeller), students experiment with different ways to launch the hovercrafts down the course. All designed to help them understand, once they're riding on the back of one in room 229, what exactly is going on.

As one student says, once she takes off her headphones and disembarks, "This is totally the most awesome thing ever."