Lesson Plan

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• Teacher Guide.doc
• Teacher Guide.pdf

Submitted by
Kimberly Fluder
Sherwood Elementary
Saginaw, Michigan

Thanks to
Dow Chemistry Teacher Summit

Summary

In this two-part lesson, students will learn about density through a teacher-led demonstration and a hands-on activity. The demonstration will give students the opportunity to observe the formation of a density tower made from common drinks. Students will then create their own density tower using simple ingredients, and then further investigate differences in density when solid objects are added to the tower.         

Grade Level

Elementary School

Objectives  

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

• Understand the meaning of density, and explain what factors make different objects have different density values.
• Identify density as a physical property of matter.
• Use appropriate vocabulary to discuss their observations.
• Predict and compare the density of different solids and liquids based on their behavior in a density tower.

Chemistry Topics

• Density
• Mixtures

Time

Teacher Preparation: 30 minutes

Lesson: Day 1: One hour; Day 2: One hour 15 minutes

Materials

Day 2 Lesson

• 8 ounce clear plastic cups (one per group)
• corn syrup (light colored, 2 bottles)
• water (1 gallon)
• vegetable oil (light colored, 2 bottles)
• a variety of solid objects: suggestions include a building block, a metal nut, and Styrofoam peanut used in shipping packages (1 of each object for each group)
• rulers (1 for each group)
• permanent markers (1 for each group)
• paper towels
• KWL chart (see Teacher Notes for explanation)
• chart paper for recording student observations
• markers for writing

Day 1 Lesson

• Large clear plastic/glass container (20 inches or taller)
• small disposable drinking cups (one per student)
• Ocean Spray Cran-Apple juice (40g sugar per serving)
• Pina Colada SoBe (25g of sugar per serving)
• G2 Gatorade blueberry-pomegranate (5g sugar per serving)
• turkey baster
• ice

Safety

• Food in the lab should be considered a chemical, not for consumption.
• Always wear safety goggles when handling chemicals in the lab.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
• Be aware of any allergies students may have prior to the experiment.

 Teacher Notes

• This article from Harvard explains the scientific concept of density. It reviews how students’ ideas about density typically progress and what problems they encounter with their thinking. Next, it tells how causal restructuring is important in gaining a deep understanding. Causal restructuring is the relation between an event and a second event, where the first event is understood to be responsible for the second.  Finally, it outlines misconceptions about density and is divided into two types—those that require learning a new causal structure and those that do not.  
• A KWL chart activates students’ background knowledge about a topic, like density, and helps to scaffold them as they ask questions and organize the information they’re learning. Teachers can create a KWL chart by hanging up three sheets of butcher paper on a classroom wall or one large chart divided into 3 columns and labeling them K, W, and L; the letters stand for “What We Know,” “What We Wonder,” and “What We Learned.”  The chart helps students activate background knowledge, combine new information with prior knowledge, and learn technical vocabulary related to density.   Teachers direct, often scribe, and monitor the development of the KWL chart, but it’s the students’ discussion that makes this such a powerful instructional procedure. See a description of KWL charts for more information, if needed.
• Start the lesson as a whole group during the demonstration, and I then suggest moving to mixed- ability small groups of 3-4 students.
• As an extension for older students, teachers could use the Steve Spangler lab to expand the layers of density to include different liquids.  Just be sure to no longer allow them to drink it when the experiment is finished!
• Suggestions for real-world connections: How Can the Study of Density Be Used in the Real World?
• The AACT Density animation is a helpful concluding task for this lesson.
• Explanation of basic terms used in this lesson:
  • Density is defined as mass per volume for a substance.
  • Mass is determined by the amount of matter in a substance, and can be defined by the number of atoms that are in the substance.
  • Volume is how much space a substance occupies.
• Explanation of the density towers:
  • The Juices used have different density values. The density of a juice is often determined by how much sugar or fruit is in it – the more sugar or fruit, the denser the juice will be. Powdered and canned juices do not work well for this experiment since they are almost entirely water. You will have to do some experimentation and label reading to find juices that are colorful and give a nice display of density if the juices mentioned in the materials section are unavailable.
  • The density tower demonstrates the amount of matter that is present in a particular volume of a liquid. In other words, if you have cup with 200ml of plain water, and a cup with 200 ml of water that has lots of sugar dissolved in it, the cup of sugar water will be heavier even though they are the same volume of liquid – the invisible sugar molecules are dispersed in the water, making it more dense, and therefore heavier.
  • Density Column Mix-up: What happens if you shake or mix up your sugar density column? The colors will not separate and go back to the rainbow, like a corn syrup-water-oil density tower. The sugar will mix evenly with the water making it miscible. Here is more information from a Steve Spangler lab.

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