Floating and Sinking #09

(grades 7-12)
Soft-bound, 64 page book, 24 reproducible task cards, full teaching notes.

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Scrutinize how some liquids float upon or sink through others. How will a candle float among these layers? Study the physics by measuring mass, displacing volumes and calculating densities. Build spring balances to measure weight and buoyancy. Discover that immersed bodies are buoyed up with a force equal to the weight of the water they displace. Eureka!

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Table of Contents for #09 Floating and Sinking:

Preparation and Support

A TOPS Model for Effective Science Teaching • Getting Ready • Gathering Materials • Sequencing Task Cards • Gaining a Whole Perspective• Long Range Objectives • Review/Test Questions

Activities and Lesson Notes

  1. 1. Density of Water
  2. 2. Density of Other Liquids
  3. 3. Liquid Pairs
  4. 4. Predicting Layers
  5. 5. Dunk the Candle
  6. 6. Specific Gravity
  7. 7. Float the Candle
  8. 8. How Now, Brown Dowel
  9. 9. The Natural Order
  10. 10. Overflow Cup
  11. 11. Density Math
  12. 12. Clay Boat
  13. 13. Neither Here Nor There
  14. 14. Three Clay Bodies
  15. 15. Spring Scale
  16. 16. Fresh Water Weigh-Ins
  17. 17. Salt Water Weigh-Ins
  18. 18. Archimedes' Principle

  20. 19. Hydrometer (1)
  21. 20. Hydrometer (2)
  22. 21. Thin Blue Line
  23. 22. Melting and Freezing
  24. 23. Fire and Water
  25. 24. Floating in Air

Supplementary Cut Outs

  1. activity 15. Weight Scale
  2. activity 20. Hydrometer Scales


Complete Master List for #09 Floating and Sinking:

Key: (1st/2nd/3rd) denote needed quantities: (1st) enough for 1 student doing all activities; (2nd) enough for 30 students working in self-paced pairs; (3rd) enough for 30 students working in pairs on the same lesson. Starred* items may be purchased below.

  1. * 1/10/10: small 10 mL graduated cylinders
  2. 1/1/1: source tap water, hot and cold
  3. * 1/10/10: gram balances. Use the equal-arm balance improvised in Weighing #05, or any lab balance.
  4. 1/1/1: box table salt
  5. 2/2/2: quart jars or equivalent with lids
  6. 1/1/1: bottle 70% isopropyl alcohol. Sold in home remedy section of pharmacies.
  7. 1/1/1: bottle 100% corn oil
  8. 1/1/1: bottle baby oil (mineral oil)
  9. * 5/45/50: large 6 ounce baby food jars with lids
  10. * 5/45/50: eyedroppers

  11. 1/1/1: roll paper towels
  12. * 1/2/4: rolls masking tape
  13. 1/5/10: jars or glasses, 8 ounces or more
  14. 1/10/10: test tubes (or small graduates)
  15. * 2/15/15: emergency candles
  16. * 1/1/1: box straight pins
  17. 1/2/5: needle-nose pliers with wire cutting edge
  18. * 1/10/10: large 100 mL graduated cylinders
  19. * 3/30/30: straight plastic drinking straws
  20. 1/2/5: paper punch tools

  21. 1/10/10: hand calculators
  22. * 0.5/5/5: cups oil-based modeling clay
  23. 1/10/10: scissors
  24. 1/10/10: plastic margarine tubs (bowls)
  25. * 1/10/10: six-inch lengths wood dowel
  26. 1/3/3: toothpicks
  27. * 1/1/1: packages birthday candles
  28. 1/10/10: paper drinking cups, 6 ounces or larger
  29. 1/5/10: medium-sized cans
  30. 1/2/10: golf balls

  31. 2/10/20: size-D batteries, dead or alive
  32. 1/4/10: centimeter rulers
  33. 1/1/1: box plastic wrap
  34. * 2/20/20: natural or synthetic corks (not rubber), wine-cork size or larger. Two smaller corks may also be used together, or larger corks may be trimmed down.
  35. 1/10/10: plastic sandwich bags
  36. 1/10/10: large cereal boxes
  37. * 2/15/20: large rubber bands
  38. * 1/1/1: roll 28 gauge steel wire
  39. 1/3/10: meter sticks
  40. * 1/10/10: paper clips

  41. * 1/1/1: spool of thread
  42. * 1/10/10: film canisters
  43. * 1/3/10: solid rubber stoppers
  44. 1/3/10: books of matches
  45. 1/3/10: plastic lids
  46. * 1/1/1: package BB shot
  47. 1/3/10: tablespoons
  48. * 1/1/1: blue food coloring with dispenser
  49. 1/10/10: ice cubes
  50. 1/2/10: helium-filled balloons

Convenient Shopping:

Baby Food Jars - assorted

without lids

Each set includes 4 small, 4 medium and 4 large glass jars.

Candles - birthday

Needed for #09 Floating and Sinking, #11 Oxidation, and #14 Kinetic Model.

Candles - emergency

cylindrical, 5 inches by about 3/4 inches diameter

Also called utility candles. A handy heating source. Correctly sized for #09 Floating and Sinking. Drip catchers not included.


16-mm film-canister, snap-on lid

Once ubiquitous, now hard to find. Needed for #09 Floating and Sinking, #16 Pressure, and #23 Rocks and Minerals.

Clay - modeling

oil-based, non-drying

Sold by the 100 gram stick, about 1/4 cup, in assorted colors (our choice). One stick serves a whole classroom for TOPS applications.

Dowel - thick

wood, 3/4 inch diameter x 6 inch length

Needed for #09 Floating and Sinking. Must float freely inside a graduated cylinder.


glass, with rubber bulbs and screw-on plastic bottle top

These have many lab uses. You may purchase them separately here, or with 1/2 ounce dropper bottles (as item #1121).

Separately, these also double as Cartesian Divers in #200 Diving into Pressure & Buoyancy. If you already have droppers, test them in advance to see if they make good 'divers': Remove plastic bottle top, if any. Dropper must float when empty, then sink with a one-squeeze-intake of water. Test that the seal between bulb and barrel is water tight: The empty dropper should float for a day or so in a glass of water, without taking on visible water.

Food Coloring - blue

liquid, dispensed in 1 fl. oz. squeeze bottle

A handy science supply used to make water more visible. Used in #39 Corn and Beans, #41 Planets and Stars, and several other TOPS modules.

Graduated Cylinder - 10 mL

shatter resistant plastic on stable base

An important lab inquiry tool for measuring small liquid volumes.

Graduated Cylinder - 100 mL

shatter resistant plastic on stable base

An important lab inquiry tool for measuring larger liquid volumes.

Gram Pocket Scale

digital, pocket size

Digitally weighs up to 500 grams, plus tare container. Sensitive to 0.1 gram in multiple weight units. Durable, but not childproof. Comes with two AAA batteries to get you started.

Paper Clips

size #1, steel, box of 100

Paper clips have 1001 uses in TOPS experiments, and science in general. Feel free to use paper clips you already have, but be aware that different brands come in different sizes and weights. In experiments where uniformity is important, don't mix brands.

Rubber Bands - assorted

10 grams each of thin, medium and thick

You get 30 grams of soft, strong, durable rubber bands: thin #16 (about 50), medium #32 (about 20), and heavy-duty #64 (about 10). These sizes are specifically selected to work in most TOPS experiments.

Stopper - cork

size #10

This cork is about 1 inch in diameter across the larger end. You may freely substitute your own synthetic wine corks trimmed to size, or pair smaller corks together. Needed for #09 Floating and Sinking.

Stopper - rubber

black rubber, size #6, no hole

Used in #09 Floating and Sinking, #14 Kinetic Model, and #22 Machines.

Straight Pins

steel, one and 1/16 inch long

Used in many TOPS experiments. Sometimes required for their magnetic properties. Don't purchase aluminum straight pins by mistake.

Straws - straight

plastic, thin

Any length straw, between 0.20 and 0.25 inches in diameter is suitable. Grocery stores generally carry straws with flexible "elbows." You can use those if you cut off the bendable section before using.

Tape - masking

3/4 inch x 55 yd roll

A handy science supply used in most TOPS modules.


light duty, 25 yd spool

Just plain old thread. Used in many TOPS titles, especially in Pendulums #34.

Wire - 28 gauge iron

bare wire

A specialty item used in #09 Floating and Sinking.

Teaching Tips for #09 Floating and Sinking:

We encourage improvisation - it's one of the main goals of our hands-on approach! You and your students might invent a simpler, sturdier or more accurate system; might ask a better question; might design a better extension. Hooray for ingenuity! When this occurs, we'd love to hear about it and share it with other educators. Please send ideas and photos to tops@canby.com.

Lesson by Lesson Objectives for #09 Floating and Sinking:

  1. Lesson 1: To experimentally confirm that the density of water is very close to 1.00 g/mL, no matter how much water you measure.
  2. Lesson 2: To experimentally determine the densities of 4 different liquids.
  3. Lesson 3: To correlate the floating and sinking properties of 4 different liquids with their density measurements.
  4. Lesson 4: To predict what floats and what sinks when water, rubbing alcohol, baby oil and corn oil are combined in various ways. To test these predictions by experiment.
  5. Lesson 5: To calculate the density of a candle by displacing water in a 100 mL graduated cylinder.
  6. Lesson 6: To compute the specific gravity of a candle using two different methods.
  7. Lesson 7: To observe that a floating candle displaces a mass of water equal to its own mass.
  8. Lesson 8: To apply concepts developed in the study of a floating candle (density, specific gravity, and water displacement) to a floating wood dowel.
  9. Lesson 9: To experimentally determine the density of oil-based lay. To review all density data collected thus far and confirm its accuracy.
  10. Lesson 10: To determine the volume of a golf ball using an overflow cup. To observe that a milliliter occupies the same volume as a cubic centimeter.
  11. Lesson 11: To calculate mass knowing density and volume. To calculate volume knowing density and mass.
  12. Lesson 12: To mold clay into a floating shape that displaces its weight in water. To reshape the same piece of clay into a sinking shape that displaces its volume in water.
  13. Lesson 13: To cover a cork with clay until its density is slightly greater than fresh water. To float this body on a layer of salt water submerged under fresh water.
  14. Lesson 14: To create 3 bodies of equal mass but unequal volume. To understand how volume affects the floating and sinking characteristics of a body.
  15. Lesson 15: To construct a sensitive spring scale that measures force in "weight units." To provide an experimental basis for the study of buoyancy and Archimedes' principle.
  16. Lesson 16: To study the relationships between weight, buoyancy and water displacement for sinking, neutral and floating bodies.
  17. Lesson 17: To study the relationships between weight, buoyancy and water displacement for sinking and floating objects in liquids of different densities.
  18. Lesson 18: To verify Archimedes' principle with a floating candle and a sinking rubber stopper.
  19. Lesson 19: To make a hydrometer. To explain how it measures density.
  20. Lesson 20: To calibrate a hydrometer. To use these calibrations to estimate the density of an unsaturated salt water solution.
  21. Lesson 21: To observe and explain the interaction of mixing liquids with different densities.
  22. Lesson 22: To observe that ice, unlike candle wax, is less dense than its own liquid. To appreciate that our environment would be radically changed if ice sank in water.
  23. Lesson 23: To ballast a floating candle so it burns just above the water line. To explain its floating and sinking characteristics in terms of density and Archimedes' principle.
  24. Lesson 24: To adjust the weight of a helium-filled balloon to float with neutral buoyancy in room air. To study its floating and sinking properties in warmer and colder air of different densities.

National Science Education Standards (NRC 1996) for #09 Floating and Sinking:

TEACHING Standards

These 24 Task Cards promote excellence in science teaching by these NSES criteria:
Teachers of science...
A: ...plan an inquiry-based science program. (p. 30)
B: ...guide and facilitate learning. (p. 32)
C: ...engage in ongoing assessment of their teaching and of student learning. (p. 37)
D: ...design and manage learning environments that provide students with the time, space, and resources needed for learning science. (p. 43)

CONTENT Standards

These 24 Task Cards contain fundamental content as defined by these NSES guidelines (p. 109).
• Represent a central event or phenomenon in the natural world.
• Represent a central scientific idea and organizing principle.
• Have rich explanatory power.
• Guide fruitful investigations.
• Apply to situations and contexts common to everyday experiences.
• Can be linked to meaningful learning experiences.
• Are developmentally appropriate for students at the grade level specified.

Unifying Concepts and Processes

NSES Framework: Systems, order, and organization • Evidence, models and explanation • Constancy, change, and measurement • Evolution and equilibrium • Form and function
Core Concepts/Processes: An immersed body is buoyed up with a force equal to the weight of the water it displaces.

Science as Inquiry (content standard A)

NSES Framework: Identify questions that can be answered through scientific investigations. • Design and conduct a scientific investigation. • Use appropriate tools and techniques to gather, analyze, and interpret data. • Develop descriptions, explanations, predictions, and models using evidence. • Think critically and logically to make the relationships between evidence and explanations. • Recognize and analyze alternative explanations and predictions. • Communicate scientific procedures and explanations. • Use mathematics in all aspects of scientific inquiry.
Core Inquiries: Measure mass, volume, density, buoyancy and specific gravity. Understand how these properties affect floating and sinking.

Physical Science (content standard B)

NSES Framework:Properties and changes of properties in matter • Motions and forces
Core Content: Buoyancy • Floating and Sinking • Archimedes' Principle • Displacement • Density • Volume • Mass • Specific Gravity • Weight • Weightless Suspension

History and Nature of Science (content standard G)

NSES Framework: Science as a human endeavor • Nature of science • History of science
Core Content: Discover what the the Greek mathematician and engineer Archimedes (287-212 BC) first discovered about the relationship between buoyancy and weight.