This activity allows students to learn the concept of solving systems of equations using candy (Smarties and Tootsie Rolls) and pennies. I have had great success with this activity, even with students who are resistant to participation with traditional teaching. Even students with very low skill levels can do this activity, since it requires no prior knowledge, and is entirely physical. You could differentiate the activity by requiring higher-skilled students to write out the algebraic systems of equations after solving each problem (there is a space in the lower right corner of each problem that could be used for this). To see an example of how students work out the problems, download the preview.
Each student will need about 60 pennies, 10 Smarties, and 10 Tootsie Rolls (you could use other types of candy, just remember to replace the names in the document). Alternatively, you could use laminated pictures of candy, and just give each student one or two pieces at the end of class as a treat.