Calculating Density Lesson Plan

Instructor: Josh Corbat

Josh has taught Earth Science and Physical Science at the High School level and holds a Master of Education degree from UNC-Chapel Hill.

This lesson plan provides guidance for teaching students how to calculate the density of solids and liquids. Students will watch a video lesson, solve practice problems, and calculate density in a hands-on activity.

Learning Objectives

After this lesson, students will be able to:

  • define density.
  • describe multiple ways in which density can be calculated.
  • calculate density of solids and liquids, given appropriate variables.


60-90 minutes

Curriculum Standards

  • NGSS 5-PS1-2.

Measure and graph quantities to provide evidence that regardless of the type of change that occurs when heating, cooling, or mixing substances, the total weight of matter is conserved.


  • Various objects for density demo (kitchen sponge, balloons, cooking oil, and water; see instructions)
  • Various objects for activity (see instructions for specific examples)
  • Density cubes
  • Rulers or other measuring devices
  • Scales
  • Large beakers and access to water


  • Ask students what they know about the terms 'dense' and 'density.' Write all ideas on the board.
  • To provide a few examples of density in the real world consider doing one or more of the following demonstrations for students:
    • Take a kitchen sponge and ask a student to hold it and describe how dense it is. Then, cut it in half and hand both halves back to the student. Did the density change? Does it feel different?
    • Have two balloons prepared, one filled with helium and one blown up by mouth. Ask students to note the difference. Why does one float?
    • Pour some cooking oil into a glass of water. Ask students to note what is happening. Why might these liquids separate so rapidly?
  • Begin the How to Calculate the Density of Solids or Liquids video lesson. Pause at 0:44, and have students write a definition of 'density' in their own words.
  • Resume the video, pausing again at 2:41. Ask:
    • How do you measure the density of a solid?
    • How do you measure the density of a liquid?
    • Why is the density of a solid measured differently than the density of a liquid?
    • When, in real life, might it be necessary to measure the density of something?
    • What types of jobs might measure density on a regular basis? Why?
  • If needed, go back to 2:39 in the video to review the steps involved in calculating density.
  • Resume the video, pausing again at 3:31, and ask a few student volunteers to describe how they would solve the example problem. Encourage the rest of the class to critique their strategies.
  • Finish playing the video while students follow along and solve the problem as the video explains it further.
  • To reinforce learning, provide another example problem (or two) and have students calculate density.

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