Salt and Potato Osmosis
Updated: Jul 31
What does salt do to our bodies ?
This Lesson Plan is part the Gardening Module of SustainEd Farms' virtual programming.
Background: Salt and Potato Osmosis
Salt is in our everyday diets; it’s in breads, cheeses, soups, pizza, and many other foods. Luckily, we need it to help balance the water levels in our bodies! Through osmosis it helps all the organs, muscles, tissues, and body fluid levels stay balanced and healthy. For example, it helps our nervous system send and receive messages and prevents dehydration. However, consuming too much salt can have a negative effect and is linked to damaged blood vessels and high blood pressure. The Center for Disease Control recommends students consume less than 2,000 mg of sodium (which is an element in salt) a day. Unfortunately the average American kid consumes over 3,000 mg of sodium per day. Because we need to find a good balance of salt intake, it’s important to know both what it does to our bodies and where it is in our diets so we can make informed choices.
Students will be able to...
Understand and explore the effect sodium has on human bodies
Sodium /ˈsōdēəm/ noun - a natural chemical element (Na) and part of the chemical makeup of table salt (NaCl), found in a variety of foods
Osmosis /äzˈmōsəs,äsˈmōsəs/ noun - the movement of water molecules from an area of high water concentration to an area of low water concentration
2 cups water
⅛ - ¼ cup salt
1. Watch the following YouTube video to see a demonstration of how to perform your own salt and potato osmosis demonstration, read the Consider the Following Questions below, and then follow the steps below to explore how salt affects our bodies.
2. Label one container “Water” and the other container “Salt Water.”
3. Pour one cup of water in the container labeled “Water”
4. Pour one cup of water and ⅛-¼ cup salt into the container labeled “Salt Water” and stir until combined
5. Cut your potato in half and make some observations.
6. Place your potato halves cut side down in each container.
7. Keep your potato halves in their containers for at least one hour and up to a full day. When ready, remove them and make observations about the changes. What do you notice about the differences in the potatoes?
8. Extension ideas:
Speed up the process of osmosis by peeling or poking holes in the potato to weaken its protective skin. Why would this speed the process up?
Explore how the amount of salt changes the rate of osmosis by putting different amounts of salt in multiple containers (ex: no salt, ⅛ cup salt, ¼ cup salt, ½ cup salt)
Consider the Following
What did the potatoes look, smell, and feel like before placing them in the water containers?
How did the potatoes act in the water when you first put them in the water? Did they float, bounce, sink, or do something else?
What did the potatoes look, smell, and feel like after placing them in the water containers?
How did the potatoes act in the water when you removed them from the water? Did they float, bounce, sink, or do something else?
What changes occurred to the two potatoes in different types of water? What caused those changes?
How do those changes in the potatoes relate to changes in our bodies when we eat a lot of salt?
What foods are you eating that are high in sodium and what foods are low in sodium? How do they make you feel?
Nutrition information about sodium/salt: Healthy Kids Association
High sodium foods and their alternatives: Healthline
Osmosis video: Amoeba Sisters
Download the PDF version of this lesson plan: