Activity 3B: Hy-Density: An Exploration of Hydrodensitometry Topic: Obesity Part of: Unit: Corpulosity: A Study of Obesity

Entire Activity Download (62 pages - 13 MB)

Individual Downloads

• Teacher Background Information (1 MB)
• Teacher Administrative Information
• Part 1 – The Golden Crown (1 MB)
• Part 2 – Just Staying Afloat (Buoyancy) (2 MB)
• Part 3 - Equal Arm Balance (1 MB)
• Part 4 – Archimedes Follow-Up (2 MB)
• Part 5 – Calculating Density of Homogeneous and Heterogeneous Materials (1 MB)
• Part 6 – It’s a Stick! It’s Clay! No, It’s Denso Man! (3 MB)

Keywords

scientific process, buoyancy, homogeneous, heterogeneous, mass, volume, weight, density, fat tissue, muscle tissue, body composition, obesity

Search Curricular Keywords

Key Concepts

buoyancy, density, mass, Archimedes, body composition, homogeneous, heterogeneous

Process Skills Utilized

observation, inference, measurement, applying formulae, scientific inquiry methods, critical thinking and scientific problem solving

Intended Grade Level - 6-8th grades & High School IPC (Integrated Physics and Chemistry)

Objectives

NOTE: If your students have sufficient background in measuring mass and volume and know how to calculate density, they may skip some of the developmental activities and proceed directly to Part 6 on simulating hydrodensitometry.

Part 1 – Hy-Density: The Golden Crown
After reading a fictional story, students will be able to:

• describe the problem-solving strategy used by Archimedes
• describe their own scientific process

Part 2 – Hy-Density: Just Staying Afloat (Buoyancy)
Using common materials, triple beam balance, and graduated cylinders, students will be able to:

• observe the buoyancy of various homogeneous objects
• combine two or more materials to observe the buoyancy of heterogeneous objects
• make inferences based upon their observations
• measure mass and volume

Part 3 - Hy-Density: Equal Arm Balance
Using simple materials, students will be able to:

• make an equal arm balance
• explain the difference between mass and weight

Part 4 – Hy-Density: Archimedes Follow-Up
Using simple materials, students will be able to:

• develop their own scientific process and then evaluate the validity of that process
• design an experiment based on the story of Archimedes and the Golden Crown
• draw a data table and collect data
• draw conclusions based upon analysis of the data

Part 5 – Hy Density: Calculating Density of Homogeneous and Heterogeneous Materials
Using common materials, students will be able to:

• calculate density
• describe the relationship among density, mass, and volume
• calculate density of homogeneous and heterogeneous materials

Part 6 – Hy-Density: It’s a Stick! It’s Clay! No, It’s Denso Man!
Using common materials, students will be able to:

• explain how adding simulated fat and muscle tissue affects density
• explain how hydrodensitometry can be used to determine body composition
• define homogeneousand heterogeneousand relate these terms to their own bodies
• collect, record, and analyze data
• draw conclusions based upon analysis of data

Activity Description

Hydrodensitometry is the “Gold Standard” for determining body composition. In our time, one of the greatest health risks facing people is obesity. However, defining obesity is not as simple as it might seem. Many people would say that standing on the bathroom scales and reading the number is the way they measure obesity. What makes the issue more complex than that is the fact that two people weighing 200 pounds may differ greatly in their body composition and overall health. One may be a body builder, in whom much of his/her body weight is due to muscle, while the other may be a “couch potato” in whom much of his/her body weight is fat tissue. It is really a matter of how much fat and fat-free mass they have. When the percentage of fat increases and fat-free mass decreases a person can become obese. This activity is not focused on obesity per se, but on body composition and how it can be measured. Knowing that most teachers do not have an underwater weighing tank in their room and that there are sensitivity issues involved in teaching adolescents about body composition, a simpler way for students to learn about the method that is considered one of the more accurate methods for determining fat and fat-free masses in an individual.

Lesson Activity Sequence:
Part 1—Hy Density: The Golden Crown
Science, Math and Language Arts activity
Fictionalized account of historical event
Contemporary introduction to Archimedes
Design to build creative frustration to lead students to find out what they don’t know—teachable moments on the way!

Part 2—Hy Density: Just Staying Afloat (Buoyancy)
Science
Observation of the buoyant nature of homogeneous and heterogeneous materials

Part 3—Hy Density: Equalizing Matters (Equal Arm Balance)
Science and Historical Technology
Build an Equal Arm Balance similar to one used during Archimedes' time.

Part 4—Hy Density: Archimedes Revisited
Science, Math and Historical Technology
Using an Equal Arm Balance students look at mass
Using an Equal Arm Balance students look at mass in water
Observation of the buoyant nature of homogenous and heterogeneous materials

Part 5—Hy Density: Alike and Different
Science and Math
Calculating the density of homogeneous and heterogeneous materials

Part 6—Hy Density: Hydrodensitometry of Denso Man & Denso Woman
Science and Health
Determining the density of a model made of materials that represent the fat and fat-free masses in the human body

Activity Materials (for 10 groups of 3-4 students for all parts of the activity)

If your students are familiar with the supporting background, some parts of the activity may be skipped. Set up a material bin for each group and you will have materials needed for any or all parts of this activity.

• 10 bins large enough to hold all materials
• 20 clear plastic cups
• 10 aluminum pie pans
• 10 graduated cylinders of each - 50 mL and 100 mL
• 10 metric rulers with binder holes
• 10 pair of scissors
• 30 Plastic Drinking Straws
• 10 sandwich size plastic bags with a Ziploc™ on them
• 10 triple beam balances (students can share if 10 balances are not available)
• 30 large paper clips
• 200 – 300 wooden craft sticks—found at craft store; 80/class of 32 students
• 10 – 30 g pieces of wax; sheets of dental wax are best if you can get some from a local dentist; 5 sheets/class of 32 students
• 10 – 50 g pieces of non-toxic/odorless/non-hardening modeling clay (do not buy colored clay), such as Permoplast™ Modeling Clay
• WATTS 42143912®; found in plumbing section at hardware store
• Tape to label the bags
• Dull knife and a cutting board to cut the clay
• 1 3cm or 4 cm piece of vinyl tubing
  • For all kits, you will need: 10 ft -7/8” (outside diameter) x 5/8” (inside diameter) clear vinyl tubing cut as follows:
    • 3cm pieces
    • 4cm pieces
• 1 “lump of solid gold” made of aluminum foil and 1 penny
  • For all kits you will need 2-3 boxes of aluminum foil
  • 10 pennies or a metal coins that have a greater density than aluminum foil
• 1 Dry Erase Marker (for teacher use only)

Suggestions for miscellaneous items

• 10 pair of tongs
• 10 thermometers
• Weight set of objects, such as washers, of known mass
• Any thing else you would like to add, such as metal washers or metal BB’s

References Used

Heymsfield SB, Lohman TG, editors, Human body composition. 2nd ed. Champaign: Human Kinetics; 2005.

Durvin JV. Taylor A. Replicability of measurements of density of the human body as determined by underwater weighing. Journal of Applied Physiology. 15:142-4, 1960 Jan.

Ferrera, Linda A. (editor). Body Mass Index. New York: Nova Biomedical Books, 2005.

MB Snijder, RM van Dam, M Visser and JC Seidell. What aspects of body fat are particularly hazardous and how do we measure them? International Journal of Epidemiology 2006; 35: 83–92

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2005, 2000 by Houghton Mifflin Company. Updated 2005. Published by Houghton Mifflin. All rights reserved.

Suggested Websites:

Background information on Archimedes
http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/
Archimedes.html

http://www.mcs.drexel.edu/~crorres/Archimedes/Crown/CrownIntro.html

http://www.math.nyu.edu/~crorres/Archimedes/contents.html

Inventions of Archimedes
http://www.math.nyu.edu/~crorres/Archimedes/contents.html

Archimedes Principle
http://www.onr.navy.mil/focus/blowballast/sub/work2.htm

Interactive Pan Balance to use online
http://illuminations.nctm.org/ActivityDetail.aspx?id=33

Making a Pan Balance
http://www.sciencetoymaker.org/copter/balance.htm

http://www.labsafety.com/refinfo/ezfacts/ezf121.htm

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