The author suggests a triangular activity diagrams that includes various components and their interdependences. Individuals participate in activities (here designated by subjects) defined by conditions provoked by the division of labour even without being fully aware of the object and reasons of such activities. Activities are performed by subjects through actions to satisfy the object of the activity which is in turn driven by given goals. Instruments or tools normally mediate activities. Tools can be physical or psychological. where the constituent elements of activities and their inter relationships are graphically depicted.