This activity is helpful for students who need practice solving systems of equations using the substitution method. This was designed with middle school students in mind, but can be used with high school students in Pre-Algebra, Algebra, or Algebra 2. They will work with a partner to complete all 8 problems. Each student is asked to solve 4 problems and check their partner's work on the other 4 problems. Answer Key Included.Looking for more middle and high school collaborative math activities?