Alaska Science Key Element A6 A student who meets the content standard should understand that forces of nature cause different types of motion, and describe the relationship between these forces and motion (Motion).
 Performance Standard Level 3, Ages 11–14 Students analyze how balanced and unbalanced forces act on familiar objects and predict or explain changes in motion that may (or may not) occur. Sample Assessment Ideas Students observe the blanket toss; describe and explain the motion of the object and the blanket at each stage; describe and explain the balance of forces at each stage. Students describe and explain forces and motion involved in bowling or other sports. Expanded Sample Assessment Idea Students investigate how the force of gravity operates over a distance and influences the motion of a marble.
 Materials “Marbles” of different materials (ball bearings, glass marbles, plastic balls, etc.), thin card or wood to make “chutes”, rulers or meter sticks. Procedure Students will: Design and construct a chute that will roll marbles onto a table. Roll a marble from different distances along the chute; measure the distance traveled on the table by the marble; record. Repeat the marble roll to establish the reproducibility of the measurements. Organize information into data tables; graph data. Repeat steps 2–4 using different marbles, table surfaces, and so on. Compare results with others in the class. Draw diagrams to shows the forces and resulting motion acting on the marble before it is released, as it is rolling down the chute, when it reaches the table, as it is rolling along the table, and when it stops moving on the table. Reflection and Revision How reproducible is the experiment? What causes the variability? How can the procedure be improved to reduce the variability? How do the results change if you change the surface of the table? The type of marble? What causes these changes? What is the pattern that describes how the distance the marble moves across the table is related to the distance from which it was rolled off the chute? What other variables (besides distance along the length of the chute) might affect the distance the marble travels across the table? Levels of Performance Stage 4 Student work is complete, correct, and shows detailed evidence of the transfer and extension of knowledge that relates forces to changes in motion. Data tables and graphs are clearly labeled, well-organized and accurately represent the observations. All five force diagrams are clearly labeled to show the appropriate forces and resulting motion. The discussion shows excellent reasoning skills, recognizes that the amount of “force” determines the motion, that a constant force (gravity) is applied down the chute, and that no new force is applied once the marble leaves the bottom of the chute, and includes a detailed error analysis section. Stage 3 Student work is mostly correct, and shows evidence of the transfer or extension of knowledge that relates forces to changes in motion. Data tables and graphs are labeled, organized and reasonable representations of the observations. Most of the force diagrams are labeled to show the appropriate force and resulting motion, although they may contain minor errors or omissions. The discussion shows reasoning skills, recognizes that force determines the motion, that a constant force (gravity) is applied down the chute, and includes an error analysis section. Stage 2 Student records some data and attempts to graph. In discussion shows limited logical reasoning. May not recognize clearly the amount or origin of “force” that determines results, or that other variables need to be controlled. May recognize that some variables need to be controlled, but is unclear on details. Stage 1 Student work is mostly incomplete, contains misconceptions relating to force and motion, data records are minimal or totally incorrect, and interpretations show limited scientific reasoning.
 Standards Cross-References ( Alaska Department of Education & Early Development Standards) National Science Education Standards The motion of an object can be described by its position, direction of motion, and speed. That motion can be measured and represented on a graph. (Page 154) An object that is not being subjected to a force will continue to move at a constant speed and in a straight line. (Page 154) If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another, depending on their direction and magnitude. Unbalanced forces will cause changes in the speed or direction of an object’s motion. (Page 154) Benchmarks An unbalanced force acting on an object changes its speed or direction of motion, or both. If the force acts toward a single center, the object’s path may curve into an orbit around the center. (Page 90) Vibrations in materials set up wavelike disturbances that spread away from the source. Sound and earthquake waves are examples. These and other waves move at different speeds in different materials. (Page 90) Human eyes respond to only a narrow range of wavelengths of electromagnetic radiation—visible light. Differences of wavelength within that range are perceived as differences in color. (Page 90)