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LAB in Density, Measurements. Last updated December 12, 2023.


In this lab, students will learn how volume and mass affect density as they make comparisons and calculations.

Grade Level

Middle and Elementary School

NGSS Alignment

This lab will help prepare your students to meet the performance expectations in the following standards:

  • 5-PS1-3: Make observations and measurements to identify materials based on their properties.
  • Science and Engineering Practices:
    • Using Mathematics and Computational Thinking
    • Analyzing and Interpreting Data
    • Planning and Carrying Out Investigations


By the end of this lab, students should be able to

  • Differentiate between density, mass and volume.
  • Calculate the density of an object.

Chemistry Topics

This lab supports students’ understanding of

  • Density
  • Mass
  • Volume
  • Measurement


Teacher Preparation: 10 minutes

Lesson: 45-60 minutes


  • 3 bags of cotton balls in numbered Ziploc baggies of equal weight and size
  • 5 equal size heavy cardboard gift boxes that you will number
  • Content suggestions for boxes: sand, cotton balls, paper clips, gravel, rice, pompom balls, cereal, feathers
  • Scales
  • Rulers

Teacher Notes

  • Prepare three numbered Ziploc baggies of cotton balls of equal mass. Then, remove the air completely from one of the bags of cotton balls, remove approximately half of the air from the second bag, and the third bag should be completely full of air, like a balloon. Each bag will have successively smaller volumes. Be sure to tell them that each bag contains the same mass and number of cotton balls.
  • Choose materials for the boxes and prefill each before the activity.
  • Depending on the number of students, you may want to make multiple sets of the 3 bags of cottons balls, and the 5 boxes. Alternatively, you could have the class work together and share collected data.
  • Optional: You may want to divide the class into five groups, and have each group complete one of the density calculations for the activity.
  • This AACT Density animation may be a helpful follow-up to this lab activity.

For the Student


Everyday people compare objects but some of the terms may lead to confusion. Often someone will say, “This is heavy” or “Wow, that’s a lot.” Are they talking about the mass, the volume or the density? During this activity, you will discover the difference between mass, volume and density and how to use these scientific terms.

Pre-lab Question

  1. How is mass measured? Give an example of a mass measurement.
  2. How is volume measured? Give an example of a volume measurement.
  3. What is the formula for density?


How does a change in volume or a change in mass affect density? Can we calculate and compare the density of several unknowns?


  • Bags of cotton balls
  • Boxes filled with unknown materials
  • Ruler
  • Scale


Part 1:

  1. Compare three baggies of cotton balls. Lift each one and see which feels like it has the greatest mass? Record your predictions as “heaviest,” “medium,” or “lightest” in the data table below.
  2. Measure the mass of each baggy and record it in the data table below.
  3. In the data table record the volume occupied inside of each baggy as “largest,” “medium,” or “smallest.”

Part 2:

  1. Lift each of the five boxes. Which box feels the heaviest? Record your predictions in the first column of the data table.
  2. Using a ruler (cm) measure the boxes to determine volume (use the formula below). Formula: Volume = Length × Height × width
  3. Use the balance to determine the mass of each box and record in the data table.
  4. Using the formula for density, calculate the density of each box. Be sure to show your work in the calculation section provided.


Part 1


Mass Prediction

Actual Mass





Part 2












Use this section to show your work for the density calculations for each box:


  1. How did the mass and volume of each of the baggies compare?
  2. Will the bags each have the same value for density? Explain.
  3. How do the volumes of each box compare?
  4. Was your prediction correct for identifying the heaviest box? Look inside the five boxes.
    a. What was inside the box with the greatest density?
    b. What was inside the box with the smallest density?
  5. What makes something feel heavy? Is it mass, volume or density? Explain
  6. Ships float and anchors sink. Hot air balloons float up into the sky. Ice floats in a glass of water. Applying what you learned in this lab, why would ice (solid water!) float in liquid water?