Page Keeley is an internationally known leader in science education. She is the developer and primary author of the award-winning Uncovering Student Ideas in Science series and the Formative Assessment- Practical Strategies Linking Assessment, Instruction, and Learning series (the "FACTs books"). Her interest in teaching for conceptual understanding and understanding students' thinking began in 1992 after reading the seminal article, Teaching for Conceptual Change- Confronting Children's Experience by Bruce Watson and Dick Konicek. Her very first assessment probe, The Mitten Problem, was based on that article. Her assessment probes and FACTs (formative assessment classroom techniques) are widely used by K-12 teachers, university professors, professional developers, and science specialists throughout the U.S. and internationally.