This specific loop puzzle has 15 questions over 2-step equations. I use this with my 7th grade Pre-AP so they are still somewhat at the beginner-intermediate level.
What is a loop puzzle? Traditionally they are called "I have, Who has?" but I use my puzzles as a class activity in the hallway. I print out the papers, put them up on the walls, and have students work through them alone or with a partner. Students start out by choosing a problem at the bottom of a random sheet, and working that problem. They then look around the hallway for their answer and go stand in front of that problem. They will then work the problem under that one. Using this approach, they will work through all 15 questions. These activities are 'self-checking' because if students don't find their answer anywhere in the hallway, they know they did something wrong. Also, they should end where they started, so they know something went wrong if they don't make it back there. Sometimes I have them work these on notebook paper, and sometimes I give them 'answer documents' to log their answers as they go so I can check their work.