The big IDEA and the PD pipeline.

The Communications Web site, http://cacm.acm.org, features more than a dozen bloggers in the [email protected] community. In each issue of Communications, we'll publish selected posts or excerpts. twitter Follow us on Twitter at http://twitter.com/blogCACM http://cacm.acm.org/blogs/blog-cacm Former Computer Science Teachers Association executive director Mark R. Nelson discusses his work with the group to overcome core challenges to computer science education.