We have developed an educational induction-heating machine for university students in teacher training faculty who have no background of physics and advanced mathematics at high school. This is involved in power electronics course in teacher training faculty taught at undergraduate level from the viewpoint of environmental and energy problem. Features of the inverter are simple circuit configuration with self-oscillation using magnetic saturable core, and soft-switching scheme. Furthermore, the influence of heated-metal materials on the inverter is examined to design it from view point of safety at classroom. Finally, the educational practice is described