Machines #22

(grades 7-12)
Soft-bound, 48 page book, 16 reproducible task cards, full teaching notes.

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Employ the TOPS advantage: build fun stuff with simple things. Devise levers, pulleys, reinvent the wheel, check gear ratios, calculate horsepower, win a tug-of-war. Use spring scales to weigh loads, measure effort, and calculate efficiency. Discover that machines save effort, but never reduce work!

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Table of Contents for #22 Machines:

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. Levers (1)
  2. 2. Work
  3. 3. Levers (2)
  4. 4. Paper Clip Pulley (1)
  5. 5. Paper Clip Pulley (2)
  6. 6. Wheel Pulley
  7. 7. Combination Pulley
  8. 8. Inclined Plane (1)
  9. 9. Inclined Plane (2)
  10. 10. What Kind of Machine?

  12. 11. What Kind of Lever?
  13. 12. Super Pulley
  14. 13. Tug-of-War
  15. 14. Wheel and Axle
  16. 15. Spin Your Wheels!
  17. 16. Horsepower

Supplementary Pages

protractor • graph paper


Complete Master List for #22 Machines:

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. 6/60/90: identical textbooks
  2. 1/10/10: meter sticks
  3. 1/10/10: large rubber stoppers
  4. 1/1/1: plastic jug of water with cap, one gallon
  5. * 1/1/1: roll of masking tape
  6. 1/10/10: rulers, centimeters or inches
  7. * 1/10/10: baby food jars with tight-fitting lids
  8. * 1/1/1: spool of thread
  9. * 1/10/10: spring scales, 2 to 3 Newton capacity (250 grams)
  10. 1/1/1: roll of plastic wrap
  11. 1/5/10: pair of scissors
  12. * 1/1/1: box of paper clips
  13. 1/10/10: ring stands (optional)
  14. * 1/5/10: single wheel pulleys
  15. 2/20/20: flexible-neck drinking straws, commonly sold in grocery stores.
  16. 1/1/2: paper punch tools
  17. 1/10/10: pieces of cardboard cut from boxes, about as long and wide as notebook paper.
  18. 2/20/20: index cards, 4x6 inches work best
  19. 1/1/2: staplers
  20. 1/1/1: bolts (optional)
  21. 1/1/1: can opener (optional)
  22. 1/1/1: nut cracker (optional)
  23. 1/1/1: broom
  24. 1/10/10: flexible wire, about 14 gauge (or a wire coat hanger and pair of cutting pliers)
  25. 1/1/1: strong smooth post, fixed upright
  26. 1/1/1: 20 foot cord or rope
  27. 1/10/10: medium-sized cans
  28. * 4/40/40: rubber bands
  29. 1/10/10: small lids from cooking oil bottles, or equivalent
  30. 1/10/10: large lids from mayonnaise jars, or equivalent
  31. 1/1/1: small nail or thumbtack
  32. 1/1/1: hammer
  33. * 2/20/20: straight pins
  34. 1/1/1: roll of string
  35. 1/1/1: flight of stairs
  36. 1/1/1: yard stick (or a one-foot ruler and string)
  37. 1/1/1: stopwatch
  38. 1/1/1: bathroom scale (optional)
  39. 1/5/10: hand calculators

Convenient Shopping:

Baby Food Jars - assorted

without lids

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

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.


single wheel

A specialty item needed for #22 Machines.

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.

Spring Scale

2.5 Newton, 250 gram capacity

A zero-adjustable scale that measures weight and force at different angles (from vertical to horizontal) to the nearest 5 grams. Spring scales with twice this capacity (500 g) gives you only half the precision (nearest 10 grams) and may lack the needed accuracy. Used in #21 Motion 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.

Stopper - rubber

black rubber, size #6, no hole

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

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.

Teaching Tips for #22 Machines:

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

Lesson by Lesson Objectives for #22 Machines:

  1. Lesson 1: To build a simple lever. To experience how this lever either reduces effort, or reduces the distance through which the effort s applied.
  2. Lesson 2: To understand the idea of "work" in a scientific sense.
  3. Lesson 3: To recognize that a lever reduces the effort required to lift a resistance but does not reduce the work.
  4. Lesson 4: To construct a weight for measuring on a spring scale. To compare a movable pulley with a fixed pulley.
  5. Lesson 5: To recognize that a simple movable pulley reduces the effort required to lift a resistance, but does not reduce the work.
  6. Lesson 6: To evaluate the efficiency of a movable wheel pulley. To recognize that work output is reduced by the weight of the pulley and frictional drag.
  7. Lesson 7: To evaluate the efficiency of a combination paper clip pulley. To calculate the effort required to lift the resistance under ideal frictionless conditions.
  8. Lesson 8: To graph how the effort required to pull a cart up an inclined plane changes with its angle of inclination.
  9. Lesson 9: To recognize that an inclined plane reduces the effort require to lift a resistance, but does not reduce the work.
  10. Lesson 10: To classify common machines as levers or inclined planes.
  11. Lesson 11: To study three different classes of levers. To classify common machines as to lever type.
  12. Lesson 12: To relate the number of strands that support a pulley to the relative distances moved by the effort and resistance.
  13. Lesson 13: To have a tug-of-war contest using a pulley system. To analyze force and distance advantages.
  14. Lesson 14: To build a working model of a wheel and axle. To calculate its ideal mechanical advantage.
  15. Lesson 15: To understand how gears work. To calculate rotational relationships between them.
  16. Lesson 16: To calculate how much horsepower can be generated by running up a flight of stairs.

National Science Education Standards (NRC 1996) for #22 Machines:

TEACHING Standards

These 16 Task Cards promote excellence in science teaching by these NSES criteria:
Teachers of science...
A: ...plan an inquiry-based science program. (p. 30)
B: and facilitate learning. (p. 32)
C: ...engage in ongoing assessment of their teaching and of student learning. (p. 37)
D: and manage learning environments that provide students with the time, space, and resources needed for learning science. (p. 43)

CONTENT Standards

These 16 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 • Form and function
Core Concepts/Processes: Machines give a force or distance advantage, but never save work.

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: Multiply force by distance to calculate work and estimate machine efficiency.

Physical Science (content standard B)

NSES Framework: Motions and forces • Conservation of energy
Core Content:Weigh loads • Measure effort • Calculate work • Compute machine efficiency • Identify levers, pulleys and inclined planes • Study gear ratios • Calculate horsepower

Science and Technology (content standard E)

NSES Framework: Abilities of technological design • Understanding about science and technology Core Content: Study levers, pulleys, inclined planes, wheels and axles, and gears.