Unit 2 – Water Basics

Lesson 1 – Freshwater VS Saltwater


Today we are learning about water ratios! If you haven’t already done, so check out the Unit 2 – Vocabulary List and the About Me page to really get a feel for this website.

If you are a teacher check out these Matching Distance Learning Google Slides. 

Did you know the ocean’s salinity (salt to water ratio) is 3.5%? That means 3.5% of the sea is salt. Did you also know that even though 71% of our planet is water, only 3% of it freshwater? And of that 3% of freshwater we have to drink only 0.5% is actually available for us to drink. That means that in order to support the 8 billion people who live on the planet, there is only 0.5% of Earth is drinking water. That is really scary, especially when you think about the fact that a human can only live three days without water.


Visualizing the amount of salt inside of the ocean, comparing the amount of saltwater to freshwater, and comparing the amount of unavailable freshwater, to available freshwater.



  1. Gallon jug
  2. Salt (4 containers)
  3. Sharpie
  4. Teaspoon
  5. Tear dropper
  6. Science journal


1. Read the quick blurb I have written at the top of the page to help students understand the importance of freshwater.

2. Have students take notes on ratios and exciting facts while performing this experiment.

3. Take a gallon and divide it into tenths. Add salt to 3.5 of the tenths.

4. Fill the rest with water and then let each student sample the water. Let them see how gross it is.

5. Ask them if they would want to drink that water every day and never have freshwater again.

6. To help them see the difference between how much saltwater and freshwater is on the planet, show them a teaspoon of freshwater, that would equal the amount of water we have available as freshwater.

7. Use a tear dropper to get one drop out of the gallon. That is how much freshwater humans, plants, and animals must share to survive because that is the only accessible water.

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