Students use highest and lowest points of land elevation around the world to find the differences.
Sea level is zero, so students will be operating with positive and negative numbers. After the students find the information on the Internet, they record the elevations on a chart and on pictures, and do the subtraction. Other problems using positives and negatives are then done. By the end of the lesson, students will see how subtracting certain positive and negative numbers works. This lesson could be a part of an interdisciplinary lesson with the social studies department.