Preschool teachers need a knowledge base that includes pedagogical and didactical knowledge together with the subject knowledge. This paper sheds light on preschool teachers’ experiences in mathematics and science teaching in the early years. The paper covers the situation in Botswana, a developing country and Sweden, a developed one. The aim is to present a comparison of the pedagogical and didactical knowledge of a preschool teacher in mathematics and science. The study highlights Pedagogical Content Knowledge (PCK) and didactical considerations of maths and science teaching in preschools with reference to varied contexts, cultures and values. The Research intends to find out existing practices and derive the best method of teaching math and science in countries with diverse cultural and traditional framework. The survey conducted used a sample of 72 preschool teachers in Sweden and 64 in Botswana. Questionnaires and Focus Group Discussions were used for data collection; quantitative as well as qualitative analysis was used to compare the groups in the research study. The findings show that the context and culture play a significant role in teaching learning process. In a developing country like Botswana, the teachers were untrained in ECE and needed professional training to acquire pedagogical and content knowledge to plan maths and science activities and use available resources effectively. In a developed country like Sweden, on the contrary, teachers were trained in ECE, who planned activities and used available resources effectively and yet emphasised on updating content knowledge through specialized training. Both the countries however, need a Science Centre, documentation of experiences, knowledge handling and an administrative support to execute the BEST PRACTICE in teaching of mathematics and science to young children.