PCK involved in the Unit is related to the analysed physics topics, as well as to its IB approach. With reference to the domain of physics topics, relevant elements are the following:

• To make teachers aware of expected difficulties, misconceptions and/or alternative conceptions in the understanding of the content (as for example “Heat as energy contained in a body”, “Temperature as a measure of heat in a body”, “Different bodies placed in the same environment have different temperatures”………………….),

• To gain ability in using Scientific Instructional Representations (models, mathematical representations,.....) by connecting them and making evident their rationale to fit students' reasoning.

• To be aware of students’ learning difficulties in sketching microscopic behaviours.

• To connect physics concepts with everyday phenomena.

• To relate observation of phenomena with students' representations and models.

With regard to the features of IB approach, teachers especially need to gain pedagogical content knowledge enabling them to “engage students in asking and answering scientific questions, designing and conducting investigations, collecting and analyzing data, developing explanations based on evidence, and communicating and justifying findings” . This mainly involves to make teachers able to:

• Provide questions to frame unit and questions for discussion

• Suggest approaches for using technologies as laboratory and cognitive tools.

• Suggest approaches for collecting and analysing data.

• Support students in designing their own investigations.

• Suggest approaches to help students construct explanations Based on Evidence

• Provide approaches for promoting science communication Baseline feature.