The new natural sciences teaching curriculum (CCNN) in Chile has been recently modified, with the purpose of giving it greater relevance to current global demands and challenges. In general terms, it shows an integrative approach that encompasses the macroscopic, microscopic and symbolic levels. At a macroscopic level, visible phenomena are studied, promoting observation and curiosity. At the microscopic level, structures and processes invisible to the naked eye are explored, encouraging analysis and critical thinking. The symbolic level uses representations and theoretical models to understand and predict phenomena. These components are progressive and coherent that seek to develop a deep understanding of science and essential scientific skills in students.

The teaching of CCNN in basic school is fundamental for the development of critical and scientific thinking of students, hence these new bases and plans promote a deeper understanding of natural phenomena, but also promote the ability of students to interconnect knowledge and apply it in several situations.

The new natural sciences curriculum in primary school seeks to integrate these three levels in a coherent and progressive way. From the earliest years, students are introduced to macroscopic concepts through direct observation and experimentation. As they progress, they are introduced to the microscopic world, allowing them to connect their initial observations with smaller, more complex processes and structures. Finally, at higher levels, the use of symbols and theoretical models are introduced, facilitating a deeper and more abstract understanding of the phenomena studied.

In this work we analyze how the selection of conceptual content and its levels of representation are organized, specifically what are the levels of representation (macroscopic, microscopic and symbolic) integrated in the new curriculum, how it is organized and how it is presented, both at the of activities, as well as resources for teaching. To do this, we work with the written records (units of analysis) of curricular bases and study plans of CCNN, from 1st - 6th grade of primary school. We use a mixed approach, through the identification, categorization and coding of information units (qualitative) and, we quantify (frequency, amplitude, diversity) to build conceptual networks and distribution maps.

The main results indicate that the selection of content is very varied, but is characterized by being discontinuous and not well structured. These results have a direct impact on the implementation of the curriculum, as well as on the design of the activities and resources that teachers select for the teaching processes.

Keywords: Natural sciences, primary school, levels of representation, prescribed curriculum, teaching.