In some respect they are being taught of the Father, Son, and Holy Spirit, but in this context they are actually being baptized in the name of the Father, the Son and the Holy Spirit. We agree that the word "baptizing" used in Mat 28:19 comes from the Greek baptizo; however, according to Strongs (G0907) and other texts it means: to immerse, submerge; to make whelmed (i.e. fully wet); used only (in the New Testament) of ceremonial ablution, especially (technically) of the ordinance of Christian baptism: — Baptist, baptize, wash.