The Swedish Schools Inspectorate (2012) made an evaluation of the quality in science teaching in year 1–3 in the Swedish compulsory school. Large differences were found among the 30 schools studied. Often teaching only consisted of mediating facts or experiments made by the teacher. The students rarely got an opportunity to learn through systematic investigations. Less than 60% of the lessons observed involved activities were the students to large extent met scientific methods. Also, good examples were found in schools were the teachers consciously let the students make hypotheses about what will happen in an experiment. In many schools the teacher use readymade teaching packages. Generally, they consist of instructions for how series of lessons with different themes may be planned and performed by using the material included. Some of the packages also include education of the teachers. According to the School Inspectorate teachers without education in science claim that with help of the packages they have been able to teach in all areas of school science. Teachers sometime use the packages as inspiration, but chose other methods for their teaching. The purpose of this study was to examine how students in primary school use concepts and to study their conceptual development during two sequences of lessons, primarily based on the student’s own documentations. Written diaries and reports of the students were analysed in order to construct their conceptual profiles and to follow their development. The assessment of the performances in relation to the knowledge requirement evaluated students ability to discuss simple questions concerning chemical processes, plan simple experiments and formulate simple question. The study shows that observations, discussions, and written documentation of simple experiments promotes conceptual development.