This learning resource focuses on understanding how to represent whole number distances relative to a fixed zero point, specifically using sea level as that reference. Students will learn to identify and calculate distances above and below this fixed point by analyzing a vertical scale. The session includes activities that encourage students to think about the significance of having a zero point when measuring height or depth. Through collaborative discussions, they will compare findings on distance calculations, reflecting on how a vertical number line aids in organizing and comparing distances. Additionally, there is a mathematical challenge involving calculations based on the defined zero point, reinforcing the lesson's objectives by applying learned concepts and showing their reasoning.