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Animation Activity: Density (0 Favorites)

ACTIVITY in Observations, Density, Inferences. Last updated February 9, 2022.


Summary

In this activity, students will use an animation to visualize density on the particulate level. There are opportunities to make qualitative and quantitative comparisons between substances.

Grade Level

Elementary School, Middle School, High School

NGSS Alignment

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

  • Scientific and Engineering Practices:
    • Developing and Using Models

Objectives

By the end of this activity, students should be able to:

  • Define density mathematically.
  • Determine whether an object will float or sink in a liquid based on their relative densities.

Chemistry Topics

This activity supports students’ understanding of:

  • Density

Time

Teacher Preparation: minimal
Lesson: 10-30 minutes

Materials

Safety

  • No specific safety precautions need to be observed for this activity.

Teacher Notes

  • All of the animations that make up the AACT Animation collection are designed for teachers to incorporate into their classroom lessons. Intentionally, these animations do not have any spoken explanations so that a teacher can speak while the animation is playing and stop the animation as needed to instruct.
  • We suggest that a teacher pause this animation at several points or watch it more than once to give students the opportunity to make notes, ask questions, and test their understanding of the concepts presented. The animation is a little over 1 minute long and moves quickly, so students will likely require pausing or multiple viewings to successfully complete the student activity sheet if you choose to use it.
    • In particular, at about 0:55, students are asked to match 4 density values with each of the 4 substances in the animation. Pause the animation here to allow students to make their guesses. (There is a screenshot of this moment included in the student activity sheet for students to record their answers on.)
  • If you assign this to students outside of class time, you can create a Student Pass that will allow students to view the animation (or any other video or ChemMatters article on the AACT website).
  • In this animation, particulate-level drawings show less dense substances with more space between particles and more dense substances with less space between particles. All particles (regardless of the type of matter) are represented as small, similarly-sized circles. It does not take into account differences in size between the atoms/molecules that make up the various substances. This animation is a very basic introduction to density and the concept that some substances will sink in water and others will float depending on their density relative to water’s.
  • For the question at the end of the animation where students are to match densities with the correct substances, they will need to recognize that lower-density materials will float and higher-density materials will sink. (The reference material in this case is water, but other liquids are explored in the extension questions.) At about 1:05, the particle diagrams are all displayed side by side so students can see how densely packed the particles are relative to the other substances.
  • Some of the extension questions provide practice with density calculations, which can be removed if you want to keep the activity on a more conceptual level.
  • The final extension question is a quick hands-on activity comparing the density of saltwater to freshwater that could be done as an at-home bonus question, an in-class demo, or a short lab. Note that if the egg is too old, it may float in freshwater as well as saltwater (it should only float in saltwater), so be sure the egg is relatively fresh.
  • Related classroom resources from the AACT Classroom Resource Library that may be used to further teach this topic:

For the Student

Lesson

As you view the animation, answer the questions below.

  1. What is the formula for calculating density?
  2. What happens to the apple when it is placed in the glass of water?
  3. How does the close-up of the apple particles compare to the close-up of the water particles?
  4. What happens to the penny when it is placed in the glass of water?
  5. How does the close-up of the penny particles compare to the close-up of the water particles?
  6. How does the close-up of the vegetable oil particles compare to the close-up of the water particles?
  7. What happens to the vegetable oil when it is poured in the glass of water?

In the screenshot below, draw a line connecting the density values on the left with the correct substances on the right.


  1. Based on the close-up views for each substance, how do the relative densities of two objects determine whether something sinks or floats?

Extension

  1. A sample of rubbing alcohol has a mass of 9.5 g and a volume of 12.0 mL. Determine the density of rubbing alcohol.
  2. Use your answers to questions 8 and 10 to predict whether each of the materials from the animation would sink or float if they were placed in rubbing alcohol. Explain your predictions.
  3. Calculate the mass of rubbing alcohol that would have the same volume as 10.0 g of vegetable oil.
  4. Try this! In a beaker or cup, pour about 1 cup of water (tap water is fine). In another beaker or cup, pour about 1 cup of water and add about ⅓ cup of salt. Stir it until the salt is mostly dissolved (it may not completely dissolve). Take a fresh egg and place it in the freshwater cup then in the saltwater cup. What is different about the egg’s behavior in the two cups? What might this have to do with density? Explain your reasoning.