Contents of materials hold an important place in the realization of the goals and tasks of initial physics and chemistry education in primary school teaching. Fourth grade students (11 years old) adopt basic concepts of various physical and chemical properties of materials. The aim of this paper is to determine the efficiency of student experiments and demonstration experiments in teaching physics and chemistry, in relation to the quality of student knowledge about materials. The research sample consisted of 136 fourth grade students in primary schools in Serbia. Experimental, comparative and descriptive-analytical methods were carried out. The survey instrument was a test (initial, final test and retest were conducted), containing two tasks on each cognitive level (Bloom-Anderson-Kratwohl taxonomy). Students who had independently performed experiments acquired greater knowledge about materials in relation to students to whom experiments have been demonstrated by the teacher. They achieved better results at the level of analysis, evaluation and creation.