Arduino is a popular and very useful tool in STEM and physics education. Teacher demonstrations, laboratory and home work of students are supported by an incredibly wide range of application examples for a very low cost. Since the heart of the Arduino board is an industrial microcontroller, it is a good chance to teach the basics of the related rules, standards and engineering-like approach of application that is essential in high quality STEM education. We discuss here the output drive capability often misinterpreted in the Arduino community and we also draw the attention to the importance of developing the right attitude.