I created this activity to help reinforce the skill of adding and subtracting fractions with unlike denominators in my 4th and 5th grade classrooms. Students complete 14 problems, then find their answers in the crack the code portion. Once they crack the code, they will have the answer to a riddle at the bottom. This way they can self check. If their answer is not in the chart, they can retry the problem. Answer sheet is included!!