CAMBRIDGE — Some people line up at stores or hit the treadmill after Thanksgiving. Others — about 2,000 of them — packed the gymnasium bleachers Friday at the Massachusetts Institute of Technology to watch a jar of honey make a slow, halting roll down a ramp until it finally nudged a blue ball to fall into a giant netted-off area full of mousetraps that sprung almost instantaneously, launching dozens of ping-pong balls into the air.
The Friday After Thanksgiving (FAT) chain reaction is an annual tradition that has exploded since its modest beginnings in the hallway of the MIT Museum 16 years ago. Nowadays, teams plan their contraptions days or weeks in advance. Family members become engineering collaborators as they work to build and design an array of interconnected mouse traps, cardboard tubes, dominoes, robots, toy trains, balloons, and balls of all kinds.
This year, more than 30 teams participated — the largest chain reaction event yet, according to Andrew Hong, who helped coordinate the event, sponsored by the MIT Museum.
Rube Goldberg-style machines that utilize a labyrinthine set of events to achieve a somewhat modest goal can be mesmerizing, and a good way to inspire kids’ interest in science and engineering. A recent advertising video that featured an elaborate machine made out of toys traditionally pitched at girls — including tea sets and a baby doll — recently went viral, garnering at least 8 million views.
But the MIT chain reaction event highlighted engineering as it more often is. Up until the very last minute, teams were troubleshooting, testing, and improvising.
They used materials harvested from their homes. They garnered laughs, applause, and cries of delighted surprise or sympathetic groans when a machine required an intervention (something organizers call “the hand of God”) to complete its task.
Shane Leamon, 13, the oldest member of a team from a Somerville-based organization called Parts and Crafts, built a contraption that involved golf balls bouncing off a drum, triggering a whirligig to spin and wind up a string, which caused a cash register drawer to open, and so on.
Jeff Del Papa, who came to act as a “maker-in-residence” and help guide Leamon and his team for two days earlier in the week, said he helps teach the children how to make their vision work.
“They say, ‘Yes, we want to do this.’ I say, ‘Here’s how you can obey the laws of physics and do this,” Del Papa said, adding that his dream is a world where more kids are interested in taking apart machines and learning how they work than in playing video games.
The effort can bridge generations and also lead to late-night buildathons.
One team, sporting matching red sweatshirts, held regular Skype meetings so that far-flung team members from Wisconsin, New Jersey, New York, and Massachusetts could all contribute to their effort. All that planning and effort culminated Thursday night in lots of construction — to integrate an unfurling flag and a tower and decorative dinosaur figurines and a plexiglass maze. All that made for an “interesting Thanksgiving,” said team member Tamara Cohen.
After 19 minutes and 30 seconds, the balloons were popped, the balls had rolled, the sand had drained, and the chain reaction was over.
Kinetic sculptor Arthur Ganson, the emcee of the event, said the spirit of the day was not just about the final chain reaction; it was in the creativity, the feeling of anticipation building for the final product.
“It’s amazing how this moment comes around once a year,” Ganson said. “I feel like I’m always in this moment.”