Pour 50 mL of corn syrup, 50 mL of water, and 50 mL of vegetable oil into three plastic cups for each group.
All common household or classroom materials can be saved or disposed of in the usual manner. Remind students to wash their hands after completing the activity. Read and follow all warnings on the label. Work with isopropyl alcohol in a well-ventilated room. Isopropyl alcohol is also irritating to eyes and skin, and may cause drowsiness or dizziness if inhaled. Keep away from heat, sparks, open flames, and hot surfaces. Isopropyl “rubbing” alcohol is a flammable liquid. Make sure you and your students wear properly fitting safety goggles. The activity sheet will serve as the Evaluate component of the 5-E lesson plan.
Students add corn syrup to layered oil and water and see the corn syrup sinks below both the oil and water.ĭownload the student activity sheet (PDF) and distribute one per student when specified in the activity.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.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 more dense than water and sinks.Students also observed that you can compare the density of a substance to the density of water by comparing the weights of equal amounts of the substance and water using a balance. In the previous lesson, students learned that density has to do with how heavy an object or substance is relative to its size, and that density determines whether an object sinks or floats. NGSS 5-PS1-3: Make observations and measurements to identify materials based on their properties.If your students have already learned the meanings of volume and mass, you can easily use those terms to define density (Density = mass/volume), and then use those terms in this lesson. We are also using “heavy”, “light”, and “weight” instead of “mass”. Note: We are purposely using the terms “size” and “amount” instead of “volume” in this lesson about density. If a liquid that is more dense than water is added to the surface of the water, it will sink. If a liquid that is less dense than water is gently added to the surface of the water, it will float on the water.If you weigh equal amounts or volumes of two different liquids, the liquid that weighs more is more dense. The density of a liquid is a measure of how heavy it is for the amount measured.A liquid, just like a solid, has its own characteristic density.Students will also be able to explain that if a liquid is more dense than water, it will sink when added to water, and if it is less dense than water, it will float. Students will be able to explain that the density of a liquid has to do with how heavy it is for the sample size.
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