Research shows that professional learning communities of teachers support their professional development.
We operate ten learning communities of high-school physics teachers, spread all over the country, who meet face to face once in two weeks during the whole school year. Since the framework of these face to face communities was found to promote teachers' professional development, we decided to adopt it to an on line community, thus enabling more teachers to participate.

The face to face community meetings aim to promote:
1) learner-centered teaching strategies;
2) motivating students to choose physics learning in high school (e.g.: through hands on experiments, cool short videos, physics in daily life);
3) deepening teachers pedagogical and content knowledge.

In order to achieve these goals, we use activities which encourage participants to be active and productive during the meetings and intertwine individual, small group work and plenum discussions. The pedagogical design of the activities enhances also the process of "Knowledge Integration".
The activities of the online community are based on the activities implemented in the face to face communities, and design principles derived from recommendations of the literature about effective technology-based learning environments.

We enact the online community using a blended program: two face to face meetings and synchronous online meetings (a total of thirty academic hours), taking place once in two weeks during the whole school year. The technological tools we use include a video conferencing platform which enables: full screen view for discussion sessions; sharing contents; small groups work in separates rooms, with the option for the teacher leaders to join each group. In addition we use knowledge sharing tools to support collaborative learning to encourage discussions and reflection about theoretical and pedagogical practices.
During the first year of the research we designed and developed the model, applying a participatory design methodology. The design team included physics education and educational technology experts; physics teacher leaders and physics teachers. During the second year and third (current) year we have operated, explored and refined the model.

Our Research goals are:
1) to explore teachers' professional development as a result of their participation in the online community;
2) to explore the process of forming a learning community.

We collected and analyzed video recordings of the community meetings, interviews and feedback questionnaires.

Findings indicate that teachers' participation in the on line community enabled them to be active and productive over the course of the meetings. Being a part of the community, provided teachers with the feeling that they are not working alone. On the contrary, they have the opportunity to consult, discuss and share. In addition, teachers implemented in their classrooms activities they experienced in the meetings. For some of the teachers this was the only possibility to benefit from belonging to a physics teachers learning community.

We will present a model of creating and operating an online learning community of teachers, and findings that indicate that the model supports teachers' professional development and the creation of a community. This research contributes to the current body of knowledge regarding teachers' professional development within the framework of an online community.