In this lesson, students will be able to explain that the density of a substance has to do with how heavy it is compared to the size of the object. Students will also be able to explain that density is a characteristic property of a substance. Students are introduced to the concept of density and that density has to do with how heavy something is relative to its size. Students are also introduced to the idea that whether a substance sinks or floats in water is a characteristic property of that substance and does not depend on the amount of the substance. Students also learn that if an object is denser than water it will sink when placed in water, and if it is less dense than water it will float.
In this lesson, students will be able to explain that the density of a liquid has to do with how heavy it is for the sample size. Students will also be able to explain that if a liquid is denser than water, it will sink when added to water, and if it is less dense than water, it will float. As a demonstration, the teacher will compare the weight of an equal amount or volume of water and corn syrup so students can observe that corn syrup is denser than water and sinks. Students will compare the weight of an equal amount or volume of water and vegetable oil and see that vegetable oil is less dense than water and floats. Students add corn syrup to layered oil and water and see the corn syrup sinks below both the oil and water.
Students experiment with density by changing the density of water, in this activity from Zoom. Students will discover that the more salt there is in the water, the denser the water is. Density is one thing that makes things float.
In this audio clip, students ask the question: Does air have weight? This is a great clip to engage students in a discussion on mass and density.
