This paper reports on the design, implementation, and evaluation processes of an activity that focused on the comparison meaning of the subtraction of integers and included the number line model as the primary representation. Finding the answer and determining the sign of the answer in the subtraction questions were targeted as the learning objectives. Four different situations that can be encountered in the subtraction questions were determined considering the magnitude and sign of minuend and subtrahend. Through the designed activity, it is expected that the students work on example questions first and then make generalizations by reflecting on the questions they solve. The activity was implemented in an elementary school with the participation of 27 seventh grade students. The analysis of the implementation process revealed that the activity was effective in supporting the students' performance of finding the difference and the sign of the difference when subtracting integers.