Interactive simulation environments can provide powerful instructional tools for addressing conceptual and procedural learning difficulties and for promoting students' motivation. Many simulations dealing with a variety of science principles and phenomena are now available to teachers and students worldwide. The abundance and wide accessibility of materials can be a double-edged sward: teachers are always happy to increase their collection of materials but the lack of knowledge and methods for evaluating these tools may prevent optimal instructional use.
The current situation presents new challenges for educating teachers to analyze and evaluate available materials and effectively incorporate them into the teaching and learning process.
A shift of focus in teacher training is indicated towards general, principled knowledge and skills and away from mere proficiency in operating specific programs. Acquiring and implementing concept-based terminology for describing, characterizing, analyzing and evaluating the instructional potential of simulation environments are vital components of such training programs.
The model we are suggesting for training teachers as evaluators and users of simulations is targeted towards:

• Developing a vocabulary and the ability to characterize, analyze and evaluate instructional simulation.
• Relating the use of simulations to learning difficulties documented by research in physics education.
• Training teachers as developers of customized, simulation-based instructional activities.

The training model consists of three phases:

1. Introduction through experiential learning
2. Characterizing, analyzing and evaluating sample instructional simulation
3. Designing instructional activities followed by school trial accompanied by action research.

We shall present the rationale, the instructional design and the details of this training approach and its implementation in pre-service and in-service teacher training programs, including examples of activities and outcomes. We shall also discuss possible variants of this program such as implementation through a WebQuest or as a distance learning activity, and issues related its optimal adaptation to specific groups of teachers.