HomeEarly LearningCountingCount By Three's! Count By Three's! (Gr. 1 - 3) This worksheet helps a child practice counting by three's. Count By Three's!.doc Count By Three's!.pdf Count By Three's!.jpg This worksheet was created by Erin Kellner, Owings Mills, Maryland. The author is a Technology Teacher at Argyle.Middle School. Tool Factory | Search | Contributing Teachers | Login | EULA | Clip Art Station