In the video clip below,courtesy of Glazier Clinics, Coach Alexander does a great job of clearly explaining the numbering system in the Zone Scheme. He uses specific plays to illustrate various blocking assignments. He also walks you through several different defensive alignments and then shows the corresponding offensive adjustment to the blocking scheme.
Glazier Clinics is a great source for many different coaching tools.
You can also checkout more videos like this one at the Glazier Clinics YouTube Channel
The YouTube video has sound, so please make sure that your sound is turned on and that you have access to the site (Some schools block access to YouTube)
The following is a review of the blocking assignemnts.
Center – Identifies the “0” and that is his blocking assignment.
Front Side Guard – Blocks the first guy to the front side of the 0
Front Side Tackle – Blocks the second man from the 0 on the front side
Front Side TE – Blocks the third man from the 0 on the front side
Back Side Guard – Blocks the first man to the back side of 0
Back Side Guard – Blocs the second man to the back side of 0
Back Side TE – Blocks the third man from the 0 on the back side
If a linebacker is stacked behind a lineman, the lineman is always counted first.