Objective

By the end of this lesson, you will understand the concept of osmosis and be able to explain how it works in biological systems.

Materials and Prep

Materials needed: 2 clear containers, water, food coloring, and a potato. Make sure to have a basic understanding of cell structure and the movement of molecules in and out of cells.

Activities

1. Prepare two containers with water, and add a few drops of food coloring to one of them to make it a different color.
2. Cut a potato into two equal pieces and place one in each container.
3. Observe the containers over the next few hours and note any changes in the potatoes and the water.

Fifth Grade Talking Points

• Osmosis is the movement of water molecules from an area of high concentration to an area of low concentration through a semi-permeable membrane. You can think of it like a water traffic jam, where water molecules try to squeeze through tiny holes in the cell wall.
• When we placed the potato in the colored water, we observed that the water moved into the potato, causing it to swell. This is because the water inside the potato had a lower concentration compared to the colored water, so osmosis caused the water to move into the potato to balance the concentrations.
• Understanding osmosis is important in biology because it helps us understand how cells regulate the movement of water and other molecules to maintain a healthy balance inside the cell.