Nowadays the receiving of the thread (yajñopavītā) is the most important part of this ceremony; its connection with the commencement of religious education is usually forgotten. The thread runs over the left shoulder and under the right arm, except during funerary rites, when it is reversed. It is renewed annually, and the old thread is burnt on the sacred fire.
"Upanayana." The Concise Oxford Dictionary of World Religions. . Encyclopedia.com. (August 15, 2018). http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/upanayana
"Upanayana." The Concise Oxford Dictionary of World Religions. . Retrieved August 15, 2018 from Encyclopedia.com: http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/upanayana