I usually like to use worksheets for helping students to understand how to solve systems of equations by graphing, and this is one of my favorites (This is from 2011; I've changed it slightly in 2012). It includes spiral review problems and problems to help students get ready for upcoming material, which you may edit to your liking.
I've used this worksheet for sub plans and had pretty good results.
The preview file is a pdf so you may see exactly what's in the file; the product file is a word document, which you may edit for your students.
keywords: graphing linear equations, solving systems of equations by graphing, simultaneous solutions, sub plans, Jonnard