Penn Students Host ‘App’ Coding Contest

PHILADELPHIA -- Fueled by coffee, Red Bull and lots of free food, 180 students took part in the 2012 PennApps hackathon Jan. 13-15 for nearly 48 sleep-deprived hours of computer coding.

The event, held once a semester since 2010 at the University of Pennsylvania’s School of Engineering and Applied Science, drew students from Penn as well as 12 other universities, including Rutgers, Penn State, Carnegie Mellon, Columbia, Harvard, Drexel and Lehigh. Broken into teams of four, student participants were tasked with building a computer program, or app, from scratch.

“In more theoretically inclined computer science departments like Penn’s, you learn a lot of challenging and interesting concepts in school,” said PennApps co-organizer Pulak Mittal, a sophomore pursuing a dual degree in the computer science department and at Penn’s Wharton School. “But there’s also this applied or practical side to computer science that is interesting in itself, and we don’t get a lot of opportunities in class to explore that. Through the hackathon our aim is to give students those opportunities.”

Though going from a hazy idea to a functioning program in less than 48 hours can be daunting, especially for beginners, PennApps had plenty of support on hand. Technical talks prior to the competition’s launch provided introductions to Web and Android program development. Other educational talks were held throughout the weekend. In addition, representatives from some of PennApps’ sponsors, which included Venmo, Google, Facebook and Tumblr, were available to mentor the student coders. 

The theme of this year’s PennApps was simplicity, striving to design streamlined apps that are easy to use. Or, as the organizers framed it, programmers should ask themselves, “Can my grandma use it?”

The results of the contest rose to meet that standard. The all-Penn winning team  produced ScratchTable, an app that can turn nearly any surface into a turntable.

“We looked online to get ideas and did some brainstorming before the contest,” said David Wang, a junior studying engineering and one of ScratchTable’s developers along with Eric O’Brien, Thomas Ly and Bezhou Feng. “We thought, what if we do something with motion, and thought it would be cool to do something related to music.”

To demonstrate their creation, the team taped a vibration-sensing microphone to a chalkboard. Their app, coded in the programming language C, translated the vibrations produced as the programmers moved chalk across the board into commands that manipulated music playing on a computer that was hooked up to the microphone. Tapping the chalk twice, for instance, made the computer skip to the next song, while drawing circles caused the music to “scratch” like a DJ spinning discs at a nightclub.

“It’s not magic,” said Feng, a bioengineering major, after his teammates tapped away at the chalkboard, controlling music without laying a finger on the computer. “It’s pretty close though.”

For their efforts, the team members won $2,500, provided by sponsor Venmo, and also captured the audience-choice award.

The second-place team, with students from Penn and Carnegie Mellon, built Grassroutes, which gives Website developers a simple way of embedding a locally tailored widget into their sites that encourages visitors to contact their congressional representatives about charitable causes with a single click of a mouse.

In third place was, designed by a team from Columbia and Penn. Their app allows users to first plot out a road trip using GoogleMaps and then identify which of their Facebook friends may live along the route, perhaps providing a way to couch-surf cross-country.

Other apps included a tool to select the perfect gift for a friend, one that allows Facebook users to enforce a time-limited break from that beloved social-networking site and another that helps bar-goers choose a new cocktail based on ingredients they enjoy.

Previous hackathon participants have parlayed their ideas into start-up companies, though Mittal noted that entrepreneurialism isn’t the event’s underlying goal.

“That happens sometimes, but the point of the hackathon is to spend a weekend just building something, doing something new,” he said.

More information about PennApps is available at

Videos of some of the hackathon teams demonstrating their creations are at