1. The document provides details of a 9th standard Social Science lesson about salinity of ocean water and the factors that affect it. 2. Key points covered in the lesson include the definition of salinity as the amount of dissolved salts in sea water, the average salinity of 35 parts per 100 grams, and factors like evaporation, rainfall, and melting ice that cause salinity levels to vary. 3. The temperature of ocean water also ranges depending on latitude, salinity, wind, and depth, with the highest average temperatures near the equator and lowest in higher latitudes.