This study aims to explore the experience and training of pre-service and in-service teachers (n = 470) using visual diagrams. For this purpose, they answered a questionnaire regarding their training and experience with them throughout their entire education. The results show that teachers' experience with visual diagrams was very limited at all educational stages and subjects. They consider them valuable for learning, but they have received little instruction on diagrams, copying existing materials rather than producing original ones. They mainly produced their own visual diagrams in Natural and Social Sciences. They also produced other type of diagrams (mainly quantitative and verbal) in non-STEM subjects. The results indicate a need to provide teachers with training and opportunities to practice with visual diagrams, and to make them competent to use them in their teaching to increase their didactic use with their students throughout the educational system.