La investigaci-n practica "educativa" -no "acerca de"- es una forma de la ensenanza, no un agregado a ella. Por su propia naturaleza no puede no ser un camino formativo para los ensenantes-investigadores. En tanto los sujetos de la accion de ensenanza pertenecen naturalmente al contexto practico de la accion, la emergencia de problemas -distorsiones teoria-practica, no apetencias cognitivas- los involucra como parte de los mismos y como agentes principales en busca de soluciones, necesariamente nuevas acciones (accion teorica, accion practica), no conocimientos nuevos. La mejora de la ensenanza por la investigaci-n practica supone primeramente que solo los practicos estan habilitados para realizarla, y luego que la investigacion practica es la forma especifica para investigar la ense-anza para mejorarla, no solo para conocerla. Finalmente, el involucramiento de los ensenantes-investigadores en la situacion -de ensenanza y de investigacion- supone que la "bœsqueda" los incluye, de forma que la investigaco-n practica es tanto una forma de la practica de la ensenanza como una accion de formacion para los ensenantes. Practical research, "educative" itself and not about, is not an attachment to teaching but a way of it. Because of its own nature it cannot avoid being a formative way for teacher-researchers. Given the fact that teaching action subjects naturally belong to the practical context of the action, the raise of problems - theory-practice hiatus, not cognitive appetence- involves the subjects not only as a component of them but as major agents looking for solutions this is, new actions (theoretical action, practical action), but not new knowledge. The teaching improvement by practical research implies firstly that only teachers are the ones able to accomplish, and then that practical research is the specific way to research into teaching in order to improve it, not just describe it. Finally, the teacher- researchers' commitment to the situation -both teaching and researching- supposes that the "search" includes them, so practical research is a path to the teaching practice as well as a formation action for the teachers themselves.