Grade Level/Course: Grade 8 Physical Science Lesson/Unit Plan Name: Graphing Our Speed/Motion Rationale/Lesson Abstract: This lesson shows students how to create a Position vs. Time graph from four examples of their own motion. It can be done together as a class, or in smaller groups. Students will sprint, skip, walk, and stroll. They will record the time to go a pre-­‐specified distance, calculate each speed, and finally, create a line on a graph for each type of motion. Students should see how steeper slopes correlate to faster speeds. Timeframe: 1 period Standard(s): Motion
1.
The velocity of an object is the rate of change of its position. As a basis for understanding this concept:
a.
Students know position is defined in relation to some choice of a standard reference point and a set
of reference directions.
b.
Students know that average speed is the total distance traveled divided by the total time elapsed
and that the speed of an object along the path traveled can vary.
c.
Students know how to solve problems involving distance, time, and average speed.
f.
Students know how to interpret graphs of position versus time and graphs of speed versus time for
motion in a single direction.
Investigation and Experimentation 9.
Scientific progress is made by asking meaningful questions and conducting careful investigations. As a
basis for understanding this concept and addressing the content in the other three strands, students should
develop their own questions and perform investigations. Students will:
d.
Recognize the slope of the linear graph as the constant in the relationship y=kx and apply this
principle in interpreting graphs constructed from data.
e. Construct appropriate graphs from data and develop quantitative statements about the relationships
between variables.
f.
Apply simple mathematic relationships to determine a missing quantity in a mathematic expression,
given the two remaining terms (including speed = distance/time, density = mass/volume, force =
pressure × area, volume = area × height).
g.
Distinguish between linear and nonlinear relationships on a graph of data.
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CC@WCCUSD 09/09/13
Instructional Resources/Materials: • Stopwatch (one for the class to share, or one for each group) • 25 meters of space • Tape or chalk to mark start and finish line. • Graph Paper, or copies of an empty graph • Calculators for students (can be shared by groups) Many smartphones have stopwatches and calculators. These may be substituted at your discretion. Activity/Lesson: Before class begins, measure out 25 meters. Mark the start and finish lines with chalk or tape. Outdoor basketball courts may work as well. In their groups, students should decide who will perform each speed: (1) sprint, (2) skip, (3) walk, and (4) stroll. Someone will use a stopwatch to measure the time to complete 25 meters at each speed. Or you may stay together as a class, and announce or display each time. Students use their data to complete the table: Distance is always 25 meters. Speed may be calculated back in the classroom. Page 2 of 5
CC@WCCUSD 09/09/13
Activity/Lesson continued: After calculating the speed for each, students should create a line on a graph representing each type of motion. Students may set up their graph on their own, or may need support in setting the scale for the graph and labeling the x-­‐ and y-­‐ axis. Distance should be on the vertical y-­‐axis. Time should be on the horizontal y-­‐ axis. This will give students a slope (change in y divided by change in x) that is equal to speed (change in distance divided by change in time). Students should plot a point for each distance and speed, and connect it to the origin (0,0). The line should be labeled with the type of motion, and its corresponding speed. All of the lines should be drawn onto the same graph, so that students can compare the lines and speeds. (See completed example below). Page 3 of 5
CC@WCCUSD 09/09/13
Activity/Lesson continued: OPTIONAL: You may also wish to demonstrate changing speed along the 25 meters. Walk for 10 meters, record the time, stop for 5 seconds, record the time, and jog the remainder of the 25 meters, record the time. This gives students an opportunity to calculate average speed (total distance divided by total time). On the graph, this demonstration shows a flat line on a Position vs. Time graph corresponds to zero motion. It also shows how parallel lines, with similar slopes, correspond to similar speeds. Page 4 of 5
CC@WCCUSD 09/09/13
Assessment: Students should have a complete table, and a completed graph, with four lines, labeled. “Sprint” should have the steepest slope. Stroll should be the most shallow. Questions for assessment: How do you calculate speed? How do you calculate average speed? Which was the fastest speed in the activity? Which line on our graph is the steepest? What do you notice about the lines on the graph as the speeds get faster? Which line on our graph is steeper—skip, or walk? Why did it come out steeper? How do you find the slope of a line on a graph? If a line has a steep slope, what does that tell you about its speed? If a line has a slope = 0, what does that tell you about its speed? Page 5 of 5
CC@WCCUSD 09/09/13