We will report on an initiative using multimedia to enhance the experience of face-to-face teaching for pre-service education students [Bachelor of Education (Primary)] learning about teaching decimal numbers. This project has been funded by the University of Melbourne and is being conducted by a team including the authors with assistance from Gary Asp, Nick Scott and Amanda Penrose.

Understanding decimal notation is a surprisingly difficult task. Research around the world over many years, as well as research in our department, shows that a full understanding is achieved by only two thirds of students of school-leaving age in many countries. Since the modern world relies upon the metric system and decimal notation in so many ways, this is an important problem for mathematics educators to address.

Multimedia presents new opportunities for teacher education. One of these is to bring "virtual children" into the lecture and tutorial room. With financial and staffing constraints reducing both the contact of lecturers with students and the amount of time spent by students on supervised teaching practice, there are real benefits to be derived from being able to study children's thinking through multimedia resources. Short movies of children working on problems, derived from our research projects, can be shown in lectures and are then available for analysis and detailed study by students at other times.

The resource provides:

• hypertextual information
  
  
• case studies illustrating common misconceptions about decimals
  
  
• activities (including computer games) and teaching strategies for children with specific misconceptions
  
  
• references and links to articles on related topics.

The case studies are presented in a range of ways including children's responses to a quiz with a text explanation of why a certain answer was chosen. Children's understanding is further explored using QuickTime video (still images and audio track) which shows interviews with the children doing tasks and explaining their thinking. The case studies both illustrate common misconceptions and give the user practise in observing both written and verbal clues about children's thinking about decimals. Research associated with the use of multimedia is developing around several themes. Firstly, the opportunity to study thinking in depth bears some similarity to the use of cases in teacher education. One issue for us is the degree to which the case presented should be "cleaned" before use. From a large collection of interviews collected in an associated research project, we have created 'textbook cases' - simplifying parts of the dialogue so that the child's ideas are clear and eliminating 'red herrings', relying here on our fairly substantial research experience. On occasion, we have amalgamated the data from several children to provide a comprehensive picture of our 'virtual child', displaying consistent behaviours over a range of situations. Secondly, we have found that the possibility of 'teachers as detectives' has been a useful theme for planning tutorial work. By presenting thinking in a manipulable form, prospective teachers are able to engage in this detective work ("what is this child thinking?") more easily than before. Students' reactions have been very encouraging and the resources have facilitated meaningful discussions in workshops.

There are four main sections:

• Background Information
  
  
• Case Studies
  
  
• Teaching
  
  
• Help

Included in the resource is:

• mathematical information
  
  
• psychological information
  
  
• pedagogical information
  
  
• research results
  
  
• lesson ideas
  
  
• photocopy masters
  
  
• computer games
  
  
• diagnostic tests

In addition, for teaching use at the university, the resource is linked to an electronic forum where students post their assignments for all class members to share, and to the home page of the subject where assignments are set. In this way the resource stands alone and yet can be easily integrated into our teaching at a variety of levels.