Elaboration of Relationship for
Science for All Americans

Following is a small sample of specific ways Physics by Inquiry addresses certain topics in Science for All Americans (SFAA). All references are to the 1994 printing of SFAA.

Chapter 1, The Nature of Science
* p. 4 (AAAS, 1994), the fourth paragraph introduces the idea of control of variables. This idea is a recurrent theme in Physics by Inquiry. A particular example may be found in the module Properties of Matter, §12 Sinking and floating, p. 60.

Exercise 12.3

A. Review the experiments and the reasoning that you used to decide whether the volume of an object affects whether it sinks or floats. Review the experiments and the reasoning that you used to decide whether the shape of an object affects whether it sinks or floats.
How did the results of the two experiments differ?

Describe how the results in each case led you to your conclusions about whether the property that was being tested affected sinking and floating.

B. Three students have performed an experiment in which they tested the sinking and floating behavior of three objects, each of the same volume but of different mass. They found that two of the objects sank while the third object floated. Consider the following discussion among them.

Student 1: "We held the volume constant and changed only the mass. Since we saw a difference in behavior, it must be due to the change in mass. So mass does affect sinking and floating."

Student 2: "In our experiment, we didn't hold everything fixed; the mass and the density changed. We can't say the mass was solely responsible for the change in behavior, but we can say that when the volume is kept the same, then changing both the mass and the density of the object affects sinking and floating."

Student 3: "That's right, we didn't change only one thing, we changed two. We didn't do the experiment correctly. We should have kept everything but the mass constant. Since we didn't, our experiment is useless; it doesn't tell us a thing."

Discuss this dialog with your partner. Do you agree with any of the students? If so, why? If not, explain why not.

C. In your answer to part A of this exercise, you may have assumed that it was possible to investigate the role of volume by changing the volume and holding all other variables constant. However, as you saw in part B, the interpretation of the results of an experiment may be more difficult if several of the variables are related in some way, as are the mass, volume, and density of an object.

Review your answer to part A. If you had assumed in your answer that all the variables but volume could be held constant, then modify your answer so that you agree with it now.

Discuss your reasoning with a staff member.

Chapter 2, The Nature of Mathematics

* p. 21 (AAAS, 1994), first paragraph, the absence of a law of conservation of volume is discussed. In the module Properties of Matter, §7 Changes in mass and volume, students perform experiments to discover under which circumstances the mass and volume of a system change.

Chapter 4, The Physical Setting

* p. 43 (AAAS, 1994), second paragraph, the position of the earth in the solar system and the universe is discussed. In the modules Astronomy by Sight: The Sun, Moon, and Stars and Astronomy by Sight: The Earth and the Solar System in Physics by Inquiry, Volumes I and II, students develop a geocentric and a heliocentric model to account for their observations of the motion of the sun, the moon, the stars, and those planets visible to the naked eye. These models also enable students to account for the phases of the moon and the seasons.

* p. 53 (AAAS, 1994), the second paragraph introduces forces and their effects. In Physics by Inquiry, Volume III, the module Dynamics will develop the concept of force and the laws of motion. In Volume II, the module Kinematics addresses in detail the description of motion in terms of operationally defined concepts of velocity and acceleration.

* p. 55 (AAAS, 1994), the first paragraph discusses the appearance of colored objects. In the module Light and Color in Volume I of Physics by Inquiry , students develop a model for the propagation of light from their observations. They compare and contrast the physical mechanism by which colored pigments differ from colored light and they synthesize their observations in predicting the appearance of pigments viewed under light of different colors.

* p. 56 (AAAS, 1994), the second paragraph deals with conductors and insulators and their electrical behavior in electric circuits. In Volume II, the module Electric Circuits builds an observationally-based model for the electric current and voltage in a circuit.

* p. 56 (AAAS, 1994), the third and fourth paragraph consider the effects of magnetic forces. In the module Electromagnets, students study the magnetic field produced by a current-carrying wire, make electromagnets, and build an electric motor.

Chapter 9, The Mathematical World

* pp. 132-134 (AAAS, 1994), the section Symbolic Relationships introduces algebraic relations. Throughout several Physics by Inquiry modules, symbolic representations of data and relations among them are extensively used. In particular, Part C: Scientific representations in Properties of Matter emphasizes graphing skills, elucidates the difference between an expression and an equality, and introduces students to proportional reasoning. This part of the module contains §13 Graphing mass and volume, §14 Interpreting algebraic expressions, §15 Interpreting the equal sign, and §16 Reasoning by analogy. Proportional reasoning is also applied in the context of solutions of solids in water in §23 Applications of analogies and §24 Applications of proportional reasoning.

The whole module Kinematics stresses algebraic relationships, symbolic statements, graphing, and mathematical modeling. These concepts are central features in Part A: Motion with constant speed,

Part B: Motion with changing speed, Part C: Graphical representations of motion, and Part D: Algebraic representations of motion.

Proportional reasoning is a strong component of the module Heat and Temperature. In §5 Distinguishing between heat capacity and specific heat and §6 Proportional reasoning with heat and temperature , students are given further practice with this type of reasoning.

* pp. 135-140 (AAAS, 1994), the section Uncertainty deals with issues relating to experimental error and the need for a quantifiable degree of confidence in one's observations. This topic is threaded through the module Properties of Matter. For instance, students determine the uncertainty in the mass and volume of several objects using commercial balances and graduated cylinders which they calibrate themselves. Using their experimental values for mass and volume the students compute the density of these objects and calculate the uncertainty in their derived values.

* pp. 140 -143 (AAAS, 1994), the section Reasoning outlines the structure of logical arguments which form the centerpiece of scientific analysis. All the modules in Physics by Inquiry have been explicitly designed to develop scientific reasoning skills and to provide practice in relating scientific concepts, representations, and models to real world phenomena. A particular example of model-based reasoning may be found in Astronomy by Sight: The Sun, the Moon, and the Stars, §6 Daily motion of the stars, p. 363.

Experiment 6.4

Place a light bulb in the center of the room to represent the sun. Obtain a ball to represent the earth, and a small figure to represent an observer on the earth at your location.

A. Hold the earth ball in such a way that it is approximately the same time for the observer that it was for you during your night observation session.

(1) Imagine yourself as the observer on the earth ball looking at Polaris.

Point in the direction, relative to the earth ball, that the observer should look to see Polaris. Note the point on the wall, ceiling, or floor at which you are pointing and place a piece of paper at that point. Write Polaris on the paper.

(2) Your instructor will choose a constellation that you observed at the night session. Repeat part 1 above for this constellation.

(3) Imagine that the observer on the earth ball is looking at a star near the northern horizon. Repeat part 1 above for this star.

B. Suppose that the sun and stars are free to move but that the earth remains fixed.

Describe how the light bulb sun must move so that the observer would see it move in the same way that you see the sun move.

Describe how the "stars" that you marked in the room must move so the observer would see them move the same way you see the corresponding stars move.

C. In part B, your viewpoint was that the sun and stars moved while the earth remained fixed. Now suppose that the sun and the stars remain stationary, but the earth rotates.

As you did in part A of Experiment 4.6, spin the "earth" slowly in a circle so that the observer would see the "sun" move from east to west.

For the observer, do the "stars" you labeled in part A appear to move in the same way that the corresponding stars moved during your night observation session? If not, resolve any inconsistency.

D. In the model in part B, the sun and stars move while the earth remains fixed. In the model in part C, the sun and stars are stationary while the earth rotates.

On the basis of the observations that you have made thus far, do you have any reason for preferring one model over the other?

Discuss your reasoning with a staff member.

Chapter 11, Common Themes

* pp. 168-172 (AAAS, 1994), the section Models discusses the wide range of applicability of models in scientific inquiry. Physics by Inquiry guides students in developing several conceptual models to account for their observations of physical phenomena. Students develop a model for current and voltage in §1-§3 of Electric Circuits, for magnetic materials in §9 of Magnets, and for the annual motion of the sun and the stars in §2 and §3 of Astronomy by Sight: The Earth and the Solar System.

Chapter 12, Habits of Mind

* p. 191 (AAAS, 1994), under the subsection Manipulation and Observation Skills, the ability to keep a notebook is included in a list of important skills. Student notebooks are an integral part of a course taught with Physics by Inquiry materials. In the notebooks students record observations, do exercises and problems, and reflect on how their understanding is evolving. In this way, they create an indispensable reference that complements the text and serves as an individualized study guide.