This could be because some of the Education graduates were already in the education field and pursuing a graduate course was a means of furthering their career or knowledge.

furthering 是动词 further 的现在分词形式。further 的意思是"促进、推进"，表示使某事物向前发展或取得进展。furthering 在这里表示"正在促进"或"持续推动"的意思。