You know those chain reactions (like this one), where a guy pushes a basketball, which hits a see-saw, which knocks over a bottle, which turns on a fan… well, you get the idea.

They’re called Rube Goldberg contraptions, and the Northwestern Organization of Design Engineers (yes, NODE) had students compete to build their own on Saturday in the Ford Design Center. Working in teams of four, students had materials such as playing cards, balloons and string, and five hours to put it all together. Here’s how they did, in photos and video: