This file includes 21 steps for deriving the quadratic formula by completing the square. Print the 21 pages, shuffle, and distribute to 21 of your students. Have your whole class put your students with the pages in order. Each student with a page will describe how to get from the previous step to their step.
Once the students are in order, they can start with the first form of the equation (a quadratic equation in normal or standard form), and go down the line describing how to get to their assigned steps through the 21 students. Students without slides can write down the steps to share with their groups after the activity.