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Measuring the Density of Liquids and Granular Materials

Name of Corresponding Unit Plan: Archaeological Documentation

Grade Level: 5-8

Common Core Standards:
RS9-10. 3. Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.

Math G-MG.2. Apply concepts of density based on area and volume in modeling situations (e.g., persons per square mile, BTUs per cubic foot).

Content Areas: Math, Science

Recommended Length/Duration: 45-60 minute period

Learning Goals: Students will understand the meaning of density and how to calculate its value.

Description/Sequence:

  1. Discuss how different materials have different qualities.  They may be solid, liquid, or gaseous.  They may be compact and heavy or expansive and light.  One of the measurable characteristics of a material is its density.
  2. Define density as the relationship between a material’s volume and its mass.  A material that is very massive but small, has a high density (e.g. iron, rock, mercury).  A material that is less massive for its size would have a low density (e.g. wood, Styrofoam).  The standard for density is water because standard metric units derive from water.  1 ml of water = 1 gram, 1l of water = 1 kilogram.  Therefore, the density of water is 1/1 g/ml  or 1/1 kg/l.  We say the density of water = 1.  Materials more dense than water will have a value greater than 1.  Materials less dense than water will have a fractional value less than 1.
  3. Describe that to find the density of a material you need to measure its volume and mass.  Measuring the volumes of liquids and granular solids can be done by pouring them into a graduated cylinder or measuring cup and reading the volume off the scale.  Their mass can be measured by weighing the filled cylinder and then subtracting the weight of the cylinder itself.
  4. Density is calculated by dividing the mass by the volume.  Work an example together.
  5. Organize students into small work groups to find the density of the various liquids and granular solids provided.
  6. After students have completed their measurements and calculations, compare findings and clarify and disagreements or questions.

Assessments: Check worksheets for accuracy..

Materials/Resources: Density of Liquids Worksheets (pdf), Scales, Calculators, Collection of various liquids and granular samples

Special Considerations: Weaker math students might be grouped with stronger students.

Scientific measurements are generally easier to take and calculate in metric than in English units.  Additional work may be needed if students are not familiar with metric measurements, or if the teacher chooses to use English units.

Extensions: Students might want to find the density of additional materials at home. 

Students might want to research the most and least dense solids, liquids, and gases.