By Yasmin Kafai

This week, students in Philadelphia have been among millions of children and young adults around the world participating in the Hour of Code (hourofcode.com), 60-minute online tutorials intended to demystify computer programming. Participants use characters and themes from Minecraft, Frozen, or Star Wars to create simulated environments and games using basic computer science concepts.

The Hour of Code is a teaser: a way to ignite students' interest in computer science. But for thousands of students in Philadelphia area schools, any interest in coding sparked by these online tutorials is likely to be snuffed out by a harsh reality: Very few public high schools offer computer science classes.

With the help of Penn doctoral student Justice Walker, I recently surveyed 111 public and private high schools in the Philadelphia region to find out what kind of computer science classes are available. In the School District of Philadelphia, just 19 high schools, representing 22 percent of all district high schools, reported offering some type of introductory computing course that goes beyond teaching students how to make PowerPoint presentations.

Opportunities for advanced computer science learning are even more limited. Only four high schools in the district offer Advanced Placement (AP) computer science, and all except one are magnet schools serving a more select group of students. Only one neighborhood high school in the district offers AP computer science.

Comparing the district's computer science offerings to a sampling of 24 area independent and parochial schools highlights the problem: 79 percent (19) of independent or parochial high schools we surveyed offer some sort of introductory computing course, and 21 percent (5) offer AP computer science.

Students without access to computing classes are missing out on a chance to develop skills in one of the hottest job markets in the United States. But a computer science education does more than provide skilled coders for the tech industry. When students learn how to code, they also learn how to think creatively and to solve problems logically - useful skills no matter what career or college path they pursue.

The fact that students in Philadelphia schools are missing out on computer science is also particularly troubling from an equity standpoint. The district overwhelmingly serves students from racial and ethnic backgrounds that are underrepresented in computer science - a field that suffers from sizeable racial/ethnic and gender imbalances. Denying computer science classes to students from these backgrounds only serves to perpetuate these troubling disparities.

Asking for any addition to the curriculum is a hard sell when there isn't enough money to put nurses in many schools. Nonetheless, I encourage parents, students, school leaders, and policymakers to make computer science a priority in the district. Ensuring that students have access to computer science - whether online or in person - is as critical as providing other basic skills and services. While other school districts across the nation also struggle to provide enough computer science courses, they are taking steps to hire teachers and offer the programs their students need.

The Hour of Code signals an important opportunity to expose students to computer science, but 60 minutes once a year should be just the beginning. All students deserve a chance to become producers and creators of tomorrow's technological innovations.

Yasmin Kafai is a professor of learning sciences at the University of Pennsylvania Graduate School of Education, the author of "Connected Code: Why Children Need to Learn Programming," and a codeveloper of scratch.mit.edu, a free youth programming site. kafai@gse.upenn.edu