The new general education curriculum was officially announced by Ministry of Education and Training in July, 2017. In that curriculum, experiential activity is compulsory and experiential activity in Maths is mentioned. It aims at making a basic and complete innovation of the quality and the effectiveness of general education. It combines teaching knowledge, educating people with vocational orientation; makes s good contribution to changing the education focusing mainly on teaching knowledge into the one that helps develop the learners' quality and competence totally; and harmoniously develops the virtue, mind, physical strength, aesthetics; well develops the learners' potentials. Basing on the study results of the research group at provincial level in 2017 and in 2018 and those of Vietnamese and international researchers, in order to carry out training mission and to train maths teachers capable of constructing the experiential activity themes for lower secondary students, we put forward the procedure and the content of the designing of experiential activity themes in teaching Maths to lower secondary students congruent with the new general education curriculum in Vietnam.