Published: Dec. 4, 2013

In just one hour, school kids, teachers and any code-curious member of the public with an Internet connection can now create their own 3-D video game using a tutorial built by a team at the University of Colorado Boulder in preparation for the global “Hour of Code” event happening the second week of December.

CU-Boulder’s game-building program allows people with zero experience coding to design their own 3-D worlds by “inflating” hand-drawn 2-D icons and then programming those objects to interact in defined ways. For example, a participant could easily create a 3-D version of the classic arcade game Frogger by inflating a frog and then writing a line of code that would tell the program to squash the frog if it collides with a truck that has also been programmed to move horizontally across the screen at a set speed. 

CU-Boulder’s online game-building tool is among a variety of self-guided tutorials that have been created for the Hour of Code, an event that aims to recruit 10 million schoolchildren to spend one hour during the week of Dec. 9-15, dubbed Computer Science Education Week, learning the basics of coding. The event, spearheaded by the nonprofit, is designed to spark excitement about coding among youth in order to bolster a future interest in computer science, a field that’s increasingly important to a wide range of careers as well as everyday life.

“Programming should be easy and exciting,” said CU-Boulder computer science Professor Alexander Repenning, who led the project. “But that’s not where we are. The perception of the public is that it’s hard and boring. Our goal is to expose a much larger as well as broader audience to programming by reinventing computer science education in public schools.”

CU-Boulder’s Hour of Code tutorial—which can be found at—builds on two decades of Repenning’s research, which has pioneered drag-and-drop programming tools for kids called AgentSheets and AgentCubes. Repenning and his team also have developed Scalable Game Design, a curriculum teachers can implement to help their students use AgentSheets and AgentCubes to learn computer science through building their own video games.

Students can use the same tools and their new computational thinking skills to build science simulations—the coding needed to lay out what should happen when a truck collides with a frog is not that different from the coding needed to outline the chemical reaction that occurs when two molecules collide, for example.

The Scalable Game Design project recently received a $2 million grant from the National Science Foundation to continue to expand nationally.

From the beginning, the purpose of Scalable Game Design was to give school kids a taste of coding that might be able to flip the often-held belief that computer programming was not something they wanted to learn.

Repenning and his team began to reach out to kids in the local Boulder Valley School District, offering video game-building workshops as an after-school activity. The participants loved it, but the kids who initially showed up were the usual suspects—boys. In subsequent years, the project was introduced into classes that were already being taught during the school day, exposing all kinds of kids who might not normally be inclined to try computer programming, especially girls and minority students, to code.

“We asked them after, ‘Did you enjoy the activity?’ And they said, ‘Yeah. We love it and we want to do more of it,’ ” Repenning said.

The program is now ubiquitous in Boulder-area middle schools, and beginning about five years ago, Repenning received a $1.5 million grant from NSF to expand the program to schools outside the local district, especially districts with widely varying demographics, from inner-city schools to extremely rural schools and Native American communities. To implement the expansion, CU-Boulder hosted trainings on campus each summer to prepare teachers to deliver the program.

During the first expansion, Repenning and his colleagues also discovered that the way the video-game curriculum was taught impacted the degree to which girls, who are vastly underrepresented in computer science, were interested in coding. Direct instruction appeared to turn girls off, while inquiry-based approaches got the girls as excited as the boys.

Repenning has since received two more NSF grants. The first, for $1.5 million, is being used to follow up on how pedagogy affects girls studying computer science. The second and most recent grant—$2 million awarded in August—recognizes the achievements of the initial expansion effort and is being used to further spread Scalable Game Design across the country.

After the initial expansion, the Scalable Game Design team measured the success of the program by gauging the interest students had in learning more about computer science after they finished designing a video game and by analyzing the games themselves to see if the design of the games demonstrated a grasp of coding concepts. With positive results in both categories, NSF gave the team a green light to further expand the program by offering some teacher-training programs online.

The Hour of Code tutorial built on the Scalable Game Design infrastructure now allows anyone who is interested to get a taste of video game programming. More information on the Hour of Code can be found at Anyone interested in participating in the Hour of Code or using CU-Boulder’s Hour of Code program in their classes can find information at

Alexander Repenning, 303-492-1349
Laura Snider, CU media relations, 303-735-0528