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Education: Student Outcomes |
Click here to search for other assets Liquid Rainbow Grade level: K-4 Theme: water cycle Activity: http://aquarius.nasa.gov/liquid_rainbow.html Big Idea When solutions of two different densities meet, the lower density (less dense) solution will move on top of the higher density (more dense) solution, resulting in a layering or stratification of the solutions. Density is an important feature of seawater since many physical and biological processes are affected by it, such as moving heat around the globe influencing climate and feeding and reproduction by marine organisms. Key Concepts Different densities of water, or solutions, will stratify to form layers.
Density of ocean water is influenced by temperature and salinity.
Cold water with dissolved salts (higher salinity) is denser than warm water without dissolved salts (low or no salinity).
In the oceans, the deep, bottom layer is colder and saltier than the surface layer.
Background Density is a property of matter that can be introduced at the elementary level by thinking of it in terms of the relationship between weight and volume. How can two objects that are the same size have different weights? The answer has to do with their density. An object's density is determined by comparing its mass to its volume. If you compare a rock and a cork that are the same size (they have equal volume), which is heavier? The rock is, because it has more mass. Thus the rock is denser than the cork because it has more mass in the same volume. Student Outcomes After completing this activity, students should be able to: Compare the basic properties of fresh and salt water (e.g., density, ability to dissolve salt, freezing point). (W: K-4) Key: C = climate / O = ocean circulation / T = 21st century technology / W = water cycle |
