Pressure class 8 is not a commonly used term. However, class 8 students learn about pressure in their science curriculum. Pressure is defined as the force acting on a unit area of a surface and is expressed in units of pascals (Pa) . The formula for pressure is P = F/A, where P is pressure, F is force, and A is the area on which the force is applied. Students also learn about atmospheric pressure, which is the pressure exerted by the weight of the atmosphere on the earths surface.