Want to solve challenging problems? Want to learn some computer science? Want to make amazing games, drawings, and songs online? This is a course that introduces computer science ideas using the programming language Scratch. It is designed for students who have at least some familiarity with computer use and the concept of variables. While the course starts with the basics of using Scratch, the programming activities throughout the course will stretch your mind and challenge you! You are encouraged to use this material with a friend, in an after school program, or in a class. This material is based upon work supported by the National Science Foundation under Grant No. 1044106. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).