Each student is given an expression card. It can be as simple or as complex as you would like. I usually do this activity several times during the course of an equations unit. The first time I do this, I use simple expressions such as 3x-7 or -2x+9. Then after we have worked with equations for a while, I start adding in expressions that contain parenthesis or where they will have to combine like terms.
Students then have to set their expression equal to another person's expression and solve. This is a good activity to use when they need practice but you hate worksheets. I included the chart to hold students accountable for their work