About 97% of the water on Earth is in the oceans. The remaining 3% is fresh water found in lakes and ponds, rivers and streams, frozen in Earth's polar regions, in the ground and in the air. In this investigation you and your students make models to explore how Earth's water is distributed.


The invesitgation can be adapted to your grade level. Younger students could focus on ocean vs. fresh water and skip the rest of the investigation. Older students could calculate percentages or prepare their own models.


To increase the level of inquiry, have students mark the bottles with their estimates before conducting the investigation and see how close they come to estimating the amount of water in Earth's oceans and elsewhere. Have them generate a list of questions they want to explore about ocean water.


Be sure to take this investigation one step further and explore what makes ocean water different from fresh water. Ocean water contains salt. You would need to add about 60 grams of salt to the ocean water bottle in this investigation to make it as salty as Earth's oceans.


Ocean water questions for further exploration: