This study aims to explore an educational learning environment that supports students to learn conceptual modelling with the unified modelling language (UML). In this study, we call the describing models "UML programming." In this paper, we show an educational UML programming environment for science, technology, engineering, art, and mathematics (STEAM) related subjects (especially for Technology or Engineering) in schools, which are able to apply from elementary school to university. At first, we explain why, what, and how doing the UML programming. In this study, we use a state machine diagram for UML programming. To draw this model, the students just put some states in rectangular shape and transitions in arrow shape. Two types of educational model notations in state machine diagram are introduced. Then, some advanced functions of the SRPS are described. They are an educational model editor, and management of users, learning tasks and models submitted by students. Next, two case studies with the SRPS are shown. One case study is adopted to the summer camp for 5th- and 6th-grade students. The participants were 20 students and were engaged in 4 hours workshop. We used a car-type robot with two DC motors, a one-touch sensor, and one infrared sensor connected to a micro:bit. The other case study is a formal technology class at one Japanese public junior high school. One teacher and five classes worked on UML programming for traffic lights. Each class had 20 9th-grade students. One student at this school was given a traffic light robot with three Light-emitting diode (LED) lights, a one-touch sensor, and one infrared sensor connected to a micro:bit. Finally, on the basis of these two case studies using our environment, we discuss the potential for innovative STEAM education with UML programming.