AbstractPiaget’s theory of cognitive development mentioned that there are four stages for cognitive development: Sensorimotor Stage, Pre-operational Stage, Concrete-operation Stage and Formal-operational Stage. Students develop different cognitive skills from algebra operation to the logical thinking in different stages. The first part of this workshop will introduce the different stages of cognitive development and suggest the relevant STEM activities appropriate to the cognitive stages. The second part is to discuss the role of M (Mathematics) in STEM. The trainings of mathematic logics and mathematical models are necessary for STEM activities and can enhance the design of research activities. Mathematics flexibility will be discussed too as we are in a dynamic STEM environment.