1. Emphasizing the External.- Imagery for diagrams.- External representations in arithmetic problem solving.- Visualisation in mathematics and graphical mediators: an experience with 11-12 year old pupils.- Visual organisers for formal mathematics.- Mediating mathematical action.- Mathematical objects, representations, and imagery.- 2. Imagery in Support of Geometry.- Images and concepts in geometrical reasoning.- Between drawing and figure.- The functions of visualisation in learning geometry.- Geometrical pictures: kinds of representation and specific processings.- 3. Linking Screen and Mental Imagery.- Overcoming physicality and the external present: cybernetic manipulatives.- On visual and symbolic representations.- The dark side of the Moon.- Ruminations about dynamic imagery (and a strong plea for research).- On designing screen images to generate mental images.- Learning as embodied action.- 4. Employing Imagery.- The importance of mental perception when creating research pictures.- Random images on mental images.- Imagery as a tool to assist the teaching of algebra.- Mathematical screen metaphors.- Exploiting mental imaging: reflections of an artist on a mathematical excursion.