My AnalysisLesson 2 -- It Begins with Good Instruction
High School Physics
Concept: Speed
Key Principle: Speed is a rate at which distance changes.
As a result of this learning experience, students should be able to:
Learning Experience:
This activity is done at the beginning of the year to help students understand the concept of speed as a rate. It is a two-tiered activity that gives students the opportunity to determine and make observations about the speeds of various objects. In each task, students will have to determine what data needs to be collected, what is an appropriate procedure for collecting the data so that it is accurate, and how to chart and analyze the data in order to answer the questions posed to each group. Students assigned to the red activity group have less sophisticated math skills than those assigned to the blue activity.
Materials needed for the red activity include stop watches; yardsticks; and a variety of objects that can move in a fairly straight path, such as mechanical wind-up toys with keys or knobs that you turn, and wheeled toys that you roll backward to initiate forward movement.
Materials needed for the blue activity include stop watches; yardsticks; a battery-powered toy car or truck that will travel at a constant speed; a non-powered vehicle such as a Matchbox car; a slant board for an incline; and graph paper.
In a whole-class discussion at the beginning of class, the teacher will introduce the concept of speed and ask students to write down a speed that they traveled on the way to school that day. Attention will be focused on the need to express speed in units. The units of speed that students traveled to school may be expressed differently for those points at which they walked versus when they may have been in vehicles. Following the whole class discussion, students will work in groups of four or five to perform an assigned activity. Directions for the activities follow.
Red Activity
Your task is to determine the speeds of any five mechanical toys, compare the speeds of the objects, and make some observations about what you found. To begin, determine which two quantities you will have to measure in order to determine the speed of each of the objects. Write the steps you will take to determine the speed of the objects. Explain your procedure in six steps or less.
Follow the procedure you developed to determine the speeds of all five objects. As you work, revise your procedure as necessary. Write down any problems you encounter in determining the speed (there will be some). Make a data chart of the data collected for each object and the speed you calculated (be sure to include the units).
Questions for your group to answer:
Blue Activity
Your task is to determine the speed of two objects: a battery-powered car moving on a horizontal surface and a non-powered car moving down an incline. Then using the data you collected, you will make some conclusions about the motion of each car.
For each trial, mark the location of the car for each second it is in motion and record the data (tables are a good idea). Be sure to include units. Write down any problems you encounter in determining the speed (there will be some). Be prepared to explain why it is important to do a number of trials for each car.
After collecting the data, plot the distance traveled versus time for each car on a sheet of graph paper. Please keep the following hints in mind: The independent variable (the variable you control) goes along the x-axis. The dependent variable (the variable you do not control) goes along the y-axis. Make the scale of your graph so that the graph is as big as possible. Label everything: graph title, axes, units.
Determine the slope for each car. What can you conclude about speed based on the motion of each car? Use information from the graph to support your answer.
Note: Developed by Leslie J. Kiernan, ASCD, and Sheila McGrath, Adlai E. Stevenson High School, Lincolnshire, Ill.