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 2, Ages 8–10 Students predict how an object’s speed, motion and direction change when outside force is applied. Sample Assessment Ideas Students explore how a change in ramp height or mass of car affects the speed, direction, and distance traveled by cars on ramps. Students observe the motion in a Newton’s cradle demonstration; explain forces and motion involved. Expanded Sample Assessment Idea Students build a miniature sled; measure the average speed at which it moves when different forces are applied.
 Materials Meter stick, wooden block with screw at end, length of light cord or fishing line, holder for weights (cup with hood or strings), weights (washers or small fishing weights), stopwatch Procedure Students will: Lay out a measured track on the table by marking off 10 cm intervals. (NOTE: The speed of the sled will change as it moves, so the accuracy of the measuring marks will be very important.) Attach the cord or line to the block (sled) and to the weight (mass) holder; position the sled so the holder hangs over the edge of the table and the sled is stationed at the beginning of the track. Add weights to the holder until the sled just starts to move. Measure the time it takes for the sled to travels the length of the track; record all measurements; calculate the speed by dividing the distance traveled by the time it took to travel that distance. Repeat the experiment (steps 3–4) two or three times. Double the number of weights in the holder and repeat steps 3–5. Organize and tabulate data; make appropriate graphs. Compare class data from different sled sizes, different materials, different masses on sleds, and so on. Reflection and Revision Are the results the same when you compare trials 1, 2 and 3? What causes the results to vary? How could the procedure be improved to reduce the amount of variability? How will the results change if the sled moves along a different track surface? What would happen if you had a pulley for the line to go over at the table’s edge? Why? Is there a pattern with the size of sled? Mass of sled? Material for the track? Levels of Performance Stage 4 Student work is complete, well-organized, and shows detailed evidence of the transfer and extension of knowledge that relates forces to an object’s speed, motion, and change in direction. All measurements, calculations, and graphs are accurate and clearly labeled. Student’s experimental analysis includes a detailed discussion of factors that affect reliability (track surface, friction, maintaining straight-line motion, etc.) and student incorporates this information to suggest appropriate experimental design changes that will reduce variability. Stage 3 Student work is mostly complete, organized, and shows some evidence of the transfer or extension of knowledge that relates forces to an object’s speed, motion, or change in direction. Most measurements, calculations, and graphs are accurate and labeled, although they may contain minor errors or omissions. Student’s experimental analysis includes a discussion of at least two factors that affect reliability (track surface, friction, maintaining straight-line motion, etc.) and student uses some of this information to suggest an experimental design change to reduce variability. Stage 2 Student work may be incomplete or poorly organized and shows little evidence of knowledge relating to forces, speed, or motion of an object. Measurements, calculations, and graphs are included but are incomplete, missing labels, or incorrect. Student’s experimental analysis, if included, may contain misconceptions or errors of reasoning. Stage 1 Student work is mostly incomplete, incorrect, or contains evidence of major misconceptions relating to forces, speed, or motion of an object.
 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) Benchmarks Changes in speed or direction of motion are caused by forces. The greater the force is, the greater the change in motion will be. The more massive an object is, the less effect a given force will have. (Page 89) How fast things move differs greatly. Some things are so slow that their journey takes a long time; others move too fast for people to even see them. (Page 89)