In this paper, I describe a professional development approach and a conceptual framework used to create critically thoughtful and media-rich science learning resources. Greater clarity about the nature of critical thinking and how to support teachers in learning to implement it are needed if we are to respond to broader calls for critical thinking both as a central goal in science education and as a key aspect in the ecology of 21st Century e-learning environments. The conceptual framework is a model of critical thinking developed by the Canadian Critical Thinking Consortium that involves embedding the teaching of five categories of intellectual tools into the teaching of curriculum content. The "tools for thought" include addressing the need for focused and relevant "background knowledge," "criteria for judgment," "thinking concepts," "thinking strategies" and the development of "habits of mind." The professional development approach engages practicing teachers through focused inquiry groups in collaboration with rich media technicians to develop the e-critical challenges (lessons). Aspects of this "comet approach" include a series of face-to-face sessions, gradual and planned for introduction to use of laptop computers, developing inquiry oriented writing teams and expert mentorship between large group face-to-face sessions. I explain the unique aspects of both the development process and the challenges in the context of a project involving twelve teachers in the creation of media-rich critical thinking lessons in science for Grade 7 students. Although project assessment data analysis is currently underway, I offer several initial conclusions in relation to the four goals of the project.