Weighing #05

(grades 5-10)
Soft-bound, 56 page book, 20 reproducible task cards, full teaching notes

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This book is about science ownership. Students improvise a serviceable and sensitive gram balance that supports all TOPS activities requiring weight measure. The physics of balance equilibrium, centering, sensitivity, restoring forces, reproducibility, trueness, mass vs. weight, all get real on instruments that students build themselves.

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Table of Contents for #05 Weighing:

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. Build an Equal-Arm Balance (1)
  2. 2. Build an Equal-Arm Balance (2)
  3. 3. Build an Equal-Arm Balance (3)
  4. 4. Seeds and Paper Clips
  5. 5. A Question of Bias
  6. 6. Paper Clip Weight Standard
  7. 7. Balance Sensitivity (1)
  8. 8. Weighing Water
  9. 9. Gram Standard
  10. 10. Lightweights
  11. 11. Heavyweights
  12. 12. Spare Change
  13. 13. Balance Sensitivity (2)

  15. 14. Coin Graph
  16. 15. Spring Scale
  17. 16. Scales and Balances
  18. 17. Going, Going, Gone
  19. 18. Letter Weighing
  20. 19. Invent a Weight Standard
  21. 20. Help Yourself

Supplementary Cut Outs

balance beams and squares • graph paper


Complete Master List for #05 Weighing:

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. 1/15/15: scissors -- heavy-duty to cut corrugated cardboard
  2. 1/5/5: bottle white glue
  3. 4/100/100: lined index cards
  4. 1/2/2: corrugated cardboard at least 30 cm long (boxes or flat sheets)
  5. * 2/40/50: straight pins
  6. * 1/3/3: boxes paper clips -- one brand only
  7. * 2/60/60: wooden clothespins
  8. 1/30/30: medium-sized tin cans
  9. * 1/3/3: rolls masking tape
  10. 1/3/3: paper punch tools

  11. 3/80/80: small paper drinking cups with flat bottoms
  12. * 10/150/150: light-duty rubber bands
  13. * 1/30/30: heavy-duty rubber bands
  14. 1/2/2: packages long-grained white rice
  15. 1/1/1: packages unpopped popcorn
  16. 1/1/1: packages pinto beans
  17. 10/100/100: coins of each kind: pennies, nickels, and dimes
  18. * 0.1/0.5/1: cups oil-based clay — 1 cup = 1/2 pound
  19. 1/2/2: packages notebook paper
  20. 1/10/10: metric rulers

  21. * 1/5/10: graduated cylinders — 10 ml capacity
  22. 1/1/1: water source
  23. 1/5/10: hand calculators (optional)
  24. 1/5/5: cups clean, dry gravel
  25. 1/5/10: size-D batteries, dead or alive
  26. 1/10/10: meter sticks or yard sticks
  27. * 1/30/30: birthday candles
  28. 1/5/10: books of matches
  29. 2/60/60: envelopes -- legal or personal size
  30. various: materials to use as a weight standard. Use whatever you have on hand. Useful items might include: thumbtacks, washers, beans, rice, straws, heavy string, clay, scissors, eyedroppers, spoons, a hole punch.
  31. 1/1/1: large bowl

Convenient Shopping:

Candles - birthday

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

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.


wooden, spring-action

These are handy lab items to keep in stock. We use them as bulb holders, tongs, clips, and more.

Graduated Cylinder - 10 mL

shatter resistant plastic on stable base

An important lab inquiry tool for measuring small liquid volumes.

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.

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.

Tape - masking

3/4 inch x 55 yd roll

A handy science supply used in most TOPS modules.

Teaching Tips for #05 Weighing:

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 #05 Weighing:

  1. Lesson 1: To begin building a sturdy, accurate equal-arm balance to use in all experiments that require weight measure.
  2. Lesson 2: To continue building a sturdy, accurate equal-arm balance to use in all experiments that require weight measure.
  3. Lesson 3: To finish building a sturdy, accurate equal-arm balance to use in all experiments that require weight measure. To learn how to center the balance and make accurate weighings.
  4. Lesson 4: To practice making accurate weight comparisons on a balance. To solve simple equations using long division.
  5. Lesson 5: To determine if the equal-arm balance weighs true. To recognize that bias results when the arms of a balance beam have unequal length.
  6. Lesson 6: To develop a weight standard based on paper clips.
  7. Lesson 7: To experimentally determine how high and low pivot positions on the balance beam affect its sensitivity and stability.
  8. Lesson 8: To accurately weigh 10 mL of water in paper clips. To use this result to establish an equivalency between paper clips and grams.
  9. Lesson 9: To trim a 20-lined sheet of notebook paper until it weighs 1 gram.
  10. Lesson 10: To cut a series of 9 paper weights from notebook paper, starting with one gram and working down to one-hundredth of a gram.
  11. Lesson 11: To tape a series of 7 rock weights together, starting with 2 grams and working up to 50 grams.
  12. Lesson 12: To practice making accurate weighings on an equal-arm balance by weighing coins to the nearest 0.01 gram.
  13. Lesson 13: To experimentally determine if the weight of the load affects the sensitivity of an equal-arm balance.
  14. Lesson 14: To graph how penny mass increases in direct proportion to number.
  15. Lesson 15: To construct a spring scale from rubber bands and calibrate it in grams.
  16. Lesson 16: To distinguish between weight that is measured on a spring scale and mass that is measured on an equal arm balance.
  17. Lesson 17: To measure how fast a birthday candle burns wax.
  18. Lesson 18: To devise a simple method for estimating postage rates. To develop a sense for how much an ounce weighs.
  19. Lesson 19: To invent a new weight standard for the equal-arm balance. To convert measure from this new standard back into grams.
  20. Lesson 20: To judge the outcome of a contest using the equal-arm balance. To have fun.

National Science Education Standards (NRC 1996) for #05 Weighing:

TEACHING Standards

These 20 Activity Sheets 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 20 Activity Sheets 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 equal-arm balance measures mass. A spring balance measures weight.

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:Understand the nature of balance sensitivity and instrument bias. • Distinguish between weight and mass.

Physical Science (content standard B)

NSES Framework: Properties and changes of properties in matter • Motions and forces
Core Content: Balance equilibrium • Centering • Sensitivity and stability • Sensitivity and load • Restoring forces • Reproducibility • Trueness • Mass and weight

Science and Technology (content standard E)

NSES Framework: Abilities of technological design • Understanding about science and technology
Core Content: Build an equal arm balance sensitive to 0.01 grams.