A toy car, a board ramp and three surfaces drive this 3-page 3rd grade friction investigation. Students follow five steps, release the car from the same spot and measure how far it rolls on carpet, a wood floor and aluminum foil, three trials each. They write the middle value for each surface, draw it as a bar on a graph scaled to 200 centimeters, and answer three questions. Page 3 gives sample data and answers. It supports NGSS 3-PS2-1 and 3.MD.3.
3-PS2-1
“Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.”
Students run the same test on three surfaces and record how far the car rolls. The key links the shortest roll on carpet to more friction.
3.MD.3
“Draw a scaled picture graph and a scaled bar graph to represent a data set with several categories.”
Part 3 has students draw one bar for each of three surfaces on a scale that goes up in steps of 20.
Five numbered steps and a photo of a toy car on a board ramp resting on two books. Students rebuild it, release the car without a push and measure the roll in centimeters.
A table with a row each for carpet, wood floor and aluminum foil, and columns for Trial 1, Trial 2, Trial 3 and Middle Value. The middle value is the one that is not the biggest and not the smallest.
A blank bar graph titled Distance the Toy Car Rolled, with a scale from 0 to 200 cm in steps of 20 and a place for one bar per surface.
Three written questions: which surface gave the farthest roll, which gave the shortest and why the car stopped sooner, and why the car must start from the same spot each time.
Sample data (carpet 40, 45, 42; wood floor 120, 115, 118; foil 150, 155, 152), the bar heights and model answers.
Try the foil first
Lay out the three surfaces before the lesson and roll the car over each once. Foil wrinkles and slides under the wheels, so tape it down before students arrive.
Middle value
Write three numbers on the board and ask which one is in the middle. Do it twice before students fill in the table, because many want to add and divide.
Predict first
Ask students to rank the three surfaces from farthest to shortest roll before they test. Compare the ranking with the graph and talk about any surprise.
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