This is a reference sheet for my Geometry students, to help them with similar shapes. The ratio of lengths, diagonals, sides, perimeters, and so forth requires a simple proportion, but if they are calculating areas or volumes of similar shapes, they need to adjust the formulas.
This reference sheet, I have found, is very helpful for them to organize their thought process. It also serves as a visual organizer and helps them work through to the correct formula.
Please download the pdf preview file first, so you can see exactly what's included; the product file is a word document, which you may personalize for your students.