The background of this research is base on how to importans teaching materialsin learning process. In learning materials text book is used in learning equationsof one variable that students cannot be constructed by them self yet. It is causedthe teacher need to develop teaching material about modul base on discovery inmaterial of linear equiton of one variable. The purpose of this research is toknow validity and practicallity about modul base on discovery. There are threesteps is done those are define, design and develop steps. The result of thisresearch showed that modul base one discovery is valid, all average 3, 60. Itmeans that the content of modul has been delated with indicators base onecompetency. Practicallity it can be seen in presentase 99,97 %. It means clear thismodul is related with students need.