This assessment probe is to elicit students’ ideas about radiation and is designed to reveal how students distinguish between irradiated and radioactive material. It is best used with grades 9–12 and should be followed up with opportunities for discussion, argumentation, and sense-making activities. After discussion and working through students’ difficulties understanding the difference between irradiation and radioactivity, students can launch into an investigation to determine the effect of differing levels of radiation on radish growth. The probe is provided in English and Spanish. A materials list, teacher notes, standards, assessment, and references are provided. This book selection also includes the Table of Contents, Preface, Acknowledgments, Dedication, About the Authors, Introduction, and Index.