Digital tools are widely used in STEM (Science, Technology, Engineering, Mathematics) education from preschool to higher education. Despite this, the use of digital screen tools in preschool physics education is limited. The infrared camera is an example of a digital tool, which visualizes surfaces’ temperatures, and offers a concrete method to investigate and understand the physical phenomenon of heat. The aim of the study was to investigate how children aged 5-6 years use infrared cameras in exploratory activities to develop their understanding of heat. The study was conducted at a preschool in central Sweden and included eight children aged 5-6 years. Data collection included participant observations, video and audio recordings and thermal imaging. The analysis focused on children's exploratory processes and meaning making using transduction as an analytical concept. The results show that the infrared camera enables children to explore heat in a concrete and engaging way. The children’s transduction chains involved the sense of touch, and dynamic and still images from the infrared camera, and were shorter and more detailed than previous studies have shown. The children showed an understanding of the importance of colors, heat transfer as a process and that actions can affect the heating of objects. The conclusion is that infrared cameras can help to visualize children's exploratory processes and understanding of heat and thus enrich physics education already at preschool age.