Sentence:  There is no single theory of <WSD>constructivism</WSD>. In fact, there are many shades and varieties of <WSD>constructivism</WSD> spanning a range of perspectives. There is also no single individual who can be identified as the founder of <WSD>constructivism</WSD>. In fact, rather than tracing a linear development along one line of philosophical thought, <WSD>constructivism</WSD> seems to circumscribe a set of thinkers, theories and approaches that spring from a plethora of historical and cultural origins. 
Meaning of the word marked with <WSD> tags:  A psychological epistemology which argues that humans generate knowledge and meaning from their experiences.