How to Read Marching Band Drill
Here is my Google Slides introduction to how to read marching band drill charts and coordinate sheets.

Marching Band Visual Framework
Here is an 18 x 24 poster of a framework of teaching marching band visual. 

Using the 1-Yard Marks in Marching Band
Here is an 18 x 24 poster to assist in teaching how to use the 1-yard marks on a football field when learning and cleaning drill.

Marking the Field
Should you find that you need to line your own football field, this guide is quite comprehensive. It was put together by band director Brendan Maltese and shared with his permission. In particular I am a fan of final page which gives measurements for spraying an ADJUSTED four step grid front to back.

Marching Examples YouTube Playlist
Here is​ a playlist of high quality marching technique examples that I like to show when teaching.