Cohesion/Adhesion #13

Table of Contents for #13 Cohesion/Adhesion:

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

CORE CURRICULUM
1. 1. Cohesion
2. 2. Heap O' Water
3. 3. Adhesion
4. 4. Creepy Crawlies
5. 5. Water Model
6. 6. Zippers
7. 7. Surface Tension
8. 8. Groovy
9. 9. Capillary Action
10. 10. Wall O' Water
11. 11. Water Lines
12. 12. Capillary Pathways
13. 13. Chromatography
14. 14. More Chromatography
15. 15. Thick Slick
16. 16. Thin Slick
17. 17. Bubbles

ENRICHMENT CURRICULUM
18. 18. Interference
19. 19. Wave Shift
20. 20. Color Bands
21. 21. Loop The Loop
22. 22. Minimum Surfaces
23. 23. Bubble Architecture
24. 24. Giant Domes

Supplementary Pages

water molecules • area grid • interference • thin films

 

Complete Master List for #13 Cohesion/Adhesion:

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. * 4/40/40: dropper bottles with droppers
2. * 1/3/3: rolls masking tape
3. * 1/1/1: bottle blue food coloring
4. 1/1/1: bottle 70% rubbing alcohol
5. 1/1/1: source tap water
6. 1/1/1: bottle Joy, Dawn or other high-suds liquid detergent
7. 1/1/1: bottle corn oil
8. 1/1/1: roll waxed paper
9. * 1/10/10: graduated cylinders, 10mL capacity
10. 1/10/10: hand calculators


11. 1/10/10: pennies
12. 1/1/1: roll soft paper towels
13. 1/10/10: scissors
14. 1/5/10: large jars or equivalent supports
15. 1/1/1: wall clock with second hand (or wristwatches)
16. * 1/10/10: generic paper plates, 9 inch diameter
17. 1/4/10: drinking glasses
18. 1/4/10: shallow bowls
19. 1/1/1: shaker of fine pepper
20. * 5/50/50: aluminum straight pins (NOT steel)


21. 1/1/1: bar of soap
22. * 1/1/1: package solid camphor
23. 2/20/20: medium styrofoam cups
24. 1/10/10: toothpicks
25. * 1/30/30: plastic drinking straws
26. 1/10/10: pieces string, 10 inches long
27. * 4/20/40: microscope slides
28. 1/4/10: candles
29. * 1/4/10: paper clips
30. * 5/30/50: medium or large baby food jars


31. * 4/20/40: thin rubber bands
32. * 1/4/10: eyedroppers
33. * 1/4/10: hand lenses
34. 1/10/10: sheets newspaper
35. 1/3/10: sets of 8 washable colored markers
36. * 1/3/10: rolls clear tape
37. 1/1/1: shaker of table salt
38. 1/10/10: plastic tubs with lids
39. 1/1/1: plastic gallon milk jug
40. * 1/1/1: bottle glycerine


41. 1/1/1: gallon distilled or deionized water (optional)
42. * 1/1/1: spool thread
43. 2/6/20: size-D batteries, dead or alive
44. 1/10/10: pieces corrugated cardboard, 2x8 inches or larger
45. 1/3/10: index cards, 4x6 inch
46. * 1/1/1: roll aluminum foil
47. 1/2/10: medium test tubes (optional)
48. 1/2/10: meter sticks
49. 1/1/1: bottle vinegar (optional)

Convenient Shopping:

Aluminum Foil

regular strength, 20 square feet x 12 inches rolls

Buy aluminum foil here as a convenience item, or for less in many grocery stores.

#1450: Aluminum Foil @ $3.00 USD per box

Baby Food Jars - assorted

without lids

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

#1260: Baby Food Jars - assorted @ $4.00 USD per dozen set

Camphor

granules

This is a specialty item for #13 Cohesion/Adhesion. Toss the tiniest specks of DRY camphor (the smaller the better), ONTO the surface skin of a glass of water. Watch them zip and spin around, fueled by the energy of breaking hydrogen bonds! If you allow water to adhere to the surface of these specks (get them wet), nothing happens.

Be aware that camphor irritates eyes, skin, mucous membranes, and is highly toxic if swallowed. Because it evaporates readily, keep tightly sealed, and use only where good air circulation is available. Maintain adult supervision during use.

#1430: Camphor @ $1.50 USD per 1/8 tsp

Dropper Bottle with Eyedropper

1/2 ounce, amber glass

Very handy for storing and conveniently dispensing small quantities of liquid. You may also purchase eyedroppers without bottles as item #1120.

#1121: Dropper Bottle with Eyedropper @ $0.90 USD each

Eyedroppers

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.

#1120: Eyedroppers @ $0.60 USD each

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.

#1500: Food Coloring - blue @ $4.30 USD each

Glycerine

liquid dispensed in 2 fl. oz. plastic bottle

Used in #13 Cohesion/Adhesion and optionally in #42 Focus Pocus. A great addition to soap solution for making strong, large bubbles.

#1510: Glycerine @ $4.40 USD each

Graduated Cylinder - 10 mL

shatter resistant plastic on stable base

An important lab inquiry tool for measuring small liquid volumes.

#1090: Graduated Cylinder - 10 mL @ $3.80 USD each

Magnifier - hand lens

3X clear plastic hand lens

You'll find many uses for this basic tool of scientific inquiry. Very nice quality for the price. Supports #17 Light, #23 Rocks and Minerals, and #42 Focus Pocus. (One 3X hand lens is also included in each #100 Triple Magnifier Kit.)

#1040: Magnifier - hand lens @ $1.35 USD each

Microscope Slides

glass, standard size

Used in #17 Light for diffraction experiments. For viewing microscope specimens, consider cutting slides, almost for free, from clear plastic bakery cartons. Smooth any sharp edges with sandpaper or an emery board.

#1180: Microscope Slides @ $2.20 USD per 10

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.

#1020: Paper Clips @ $1.40 USD per box

Paper Plates

9-inch diameter, generic white

A classic ripple edge-design, with wide application in TOPS experiments. Buy these here for convenience, or for less at your local grocery store.

#1200: Paper Plates @ $2.00 USD per pkg of 50

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.

#1140: Rubber Bands - assorted @ $1.30 USD per bag

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.

#1070: Straws - straight @ $1.40 USD per bundle of 50

Tape - clear

3/4 inch x 1000 inch roll

Your standard desk tape with matte write-on surface.

#1011: Tape - clear @ $1.90 USD each

Tape - masking

3/4 inch x 60 yd roll

A handy science supply used in most TOPS modules.

#1010: Tape - masking @ $1.20 USD roll

Thread

light duty, 25 yd spool

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

#1130: Thread @ $0.25 USD per spool

Teaching Tips for #13 Cohesion/Adhesion:

ABOUT CAMPHOR: Toss the tiniest specks of dry camphor (the smaller the better), onto the surface skin of a glass of water (activity 6, step 4). Watch them zip and spin around, fueled by the energy of breaking hydrogen bonds! Don't allow water to adhere to the surface of these specks. If they get wet, adhesive water will surround and immobilize them. Camphor specks need to skate on the water to move freely, not swim in it.

ABOUT AMMONIA: "I am the one who called this past winter and asked if using colored/scented ammonia would be OK with TOPS Analysis because I couldn't get any plain ammonia here in Italy. Ron told me to go ahead and use the colored (yellow) and scented (lemon) ammonia and to tell him what happened.

The conclusion of all our experiments with yellow lemon-scented ammonia was that it was much weaker than normal, plain ammonia. When titrating with vinegar, for example, it took only 1 drop of vinegar to neutralize 1 drop of the colored, scented ammonia! Instead of almost 2:1, the ratio was 1:1. So, our numbers were all off, compared to the teacher's notes, but we were able to do all the experiments and the boys learned a great deal! (And I was reminded of all that I had buried somewhere in my brain!)"

From M.C. in Italy

Lesson by Lesson Objectives for #13 Cohesion/Adhesion:

1. Lesson 1: To compare the size and shape of drops of different liquids. To order these liquids according to their relative cohesive strength.
2. Lesson 2: To observe how cohesion holds water together on a penny. To recognize that soap weakens this cohesion.
3. Lesson 3: To compare run times and trail patterns for various liquids that move down a wax paper ramp. To observe that different liquids adhere to wax paper with different strengths.
4. Lesson 4: To observe the interactions of tap water, rubbing alcohol and soapy water with corn oil and waxed paper surfaces. To explain these interactions in terms of adhesion and cohesion.
5. Lesson 5: To model the structure of water. To understand its cohesiveness in terms of electrostatic attraction.
6. Lesson 6: To observe how small particles on the surface of water move in response to breaking hydrogen bonds.
7. Lesson 7: To recognize that water cohesion creates an unbroken skin-like surface strong enough to support a pin. To distinguish between this phenomenon and floating.
8. Lesson 8: To explain interactions of water, styrofoam and string in terms of adhesion, cohesion and surface tension.
9. Lesson 9: To observe how water moves between glass slides by capillary action. To understand how adhesion and cohesion drive this process.
10. Lesson 10: To understand why capillary action increases as water is squeezed within narrower space between glass.
11. Lesson 11: To observe and explain surface interactions between glass and water in terms of cohesion, adhesion, surface tension and capillary action.
12. Lesson 12: To study capillary action in a paper towel. To relate this process to the transpiration of water through trees.
13. Lesson 13: To separate ink spots into their component colors using chromatography.
14. Lesson 14: To develop a color mixing chart based on color chromatograms. To model why some dye combinations separate by capillary action better than others.
15. Lesson 15: To form an oil slick on water with a drop of corn oil, and disperse it with a drop of soapy water. To understand the molecular forces at play.
16. Lesson 16: To form oil films on water that reflect color by light interference. To understand this phenomenon as a function of film thickness.
17. Lesson 17: To associate reduced surface tension in water with the formation of long-lasting surface bubbles. To admire the varied color patterns that result when light reflect off the surface of a thin bubble film.
18. Lesson 18: To graph how wave trains interfere constructively when they are in phase, and destructively as they shift out of phase.
19. Lesson 19: To model how thin oil films and thin soap films interfere with white light to produce a spectrum of color.
20. Lesson 20: To observe bands of color reflected in soap film. To interpret this phenomenon in terms of light interference and variable film thickess.
21. Lesson 21: To observe how cohesive forces in soap film contract it into a shape that minimizes total surface area.
22. Lesson 22: To recognize that cohesive forces always contract soap film into shapes that minimize surface area, in both two and three dimensions.
23. Lesson 23: To further explore the geometry of soap films.
24. Lesson 24: To explore variables that influence bubble size.

National Science Education Standards (NRC 1996) for #13 Cohesion/Adhesion:

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: Model hydrogen bonding - how water holds itself together. • Bubbles form shapes that minimize surface tension.

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 connect 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: Why do some liquids heap, roll, creep and soak in, and others do not? • Account for color patterns on the surface of an oil slick and a bubble.

Physical Science (content standard B)

NSES Framework:Properties and changes of properties in matter • Motions and forces • Interactions of energy and matter
Core Content:Cohesion • Adhesion • Surface tension • Hydrogen bonds • Ink-spot chromatography • Oil slicks • Light interference • Bubble geometry

Science in Personal and Social Perspectives (content standard F)

NSES Framework: Environmental quality
Core Content: Investigate the surface chemistry of oil spills.