How Far Can You Make a Toy Car Go?

Transcription

1 How Far Can You Make a Toy Car Go? Using Hot Wheels (tracks and a toy car), try to make the car travel the longest distance possible. There are 3 things that you can do to affect the distance it travels: add weight, change the steepness (height) of the track and add more than one length of track. Pick one of these variables to test, plan how you will test the variable you selected (make sure that it is a fair test ), and measure and record the distances for your results. Then draw some conclusions based on the trials from your investigation. 1 of 11

2 Suggested Grade Span 3 5 Task Using Hot Wheels (tracks and a toy car), try to make the car travel the longest distance possible. There are 3 things that you can do to affect the distance it travels: add weight, change the steepness (height) of the track and add more than one length of track. Pick one of these variables to test, plan how you will test the variable you selected (make sure that it is a fair test ), and measure and record the distances for your results. Then draw some conclusions based on the trials from your investigation. Big Idea and Unifying Concept Cause and effect Physical Science Concept Motion and forces Mathematics Concepts Data collection, organization and analysis Graphs, tables and representations Measurements Time Required for the Task Approximately two to three hour-long sessions. Context This is one of several investigations I use to introduce and explore testing variables during our unit on motion. We begin the unit investigating inertia, using ramps and balls of various sizes and weights. We also brainstorm many everyday examples of inertia in our lives and in things we have observed. Students, therefore, will have some understanding of the things (forces) that affect how far an object moves. This activity focuses their attention on how changing one thing (vthe ariable) will influence distance or the object s inertia. This investigation will enable students to explore variables and to recognize their importance in conducting a fair test. It will 2 of 11

3 also increase their knowledge of specific motion-related concepts and enable them to practice their inquiry process skills. What the Task Accomplishes By designing an investigation to test variables, students will demonstrate their understanding of what a variable is, how to test using a variable, and its effect on the results they observe. They will also practice planning and carrying out an investigation, drawing conclusions, and communicating what they have learned to others. This activity will allow the teacher to assess students understanding of variables, fair tests, use of many process skills, and the concepts of inertia, gravity, mass and motion. How the Student Will Investigate Students must first decide which variable they will look at to answer this question: Which variable do they think will make the car go the farthest (making a prediction based on prior knowledge and experiences)? Then, on a recording sheet, they will plan how they will investigate this by writing their testable question (hypothesis), drawing a picture (visual representation) and describing their procedure. Once they have done this, they will set up their materials to test and record all results that they observe. Their results should be detailed and include distances measured (with units labeled) in each trial. In drawing their conclusions, students should carefully study their results and consider the effect the variable had on those results. Interdisciplinary Links and Extensions Science Once students have tested for one variable that changes the distance traveled, they might be challenged to experiment with ways to have changes reinforce or cancel each other. Reinforcing effects can be created by developing a combination for optimum distance considering all three variables within some given parameters (such as a maximum for the height of the ramp); or students might increase one variable and decrease another to create a canceling effect. Small groups could conduct tests and contribute their data to plotting a class graph that reveals relationships between variables. They might also explore concepts of friction (by changing surfaces or adding weight) and simple machines (inclined planes). Note: While this investigation concentrated on identifying and controlling variables, it did not stress writing a testable question. Further exploration with variables should encourage students to try if...then forms of testable hypotheses (such as: If I increase the height of the ramp, then the car will go farther ) or to use the variable to construct a testable question (such as: If I increase the height of the ramp, will the car go farther? ). Helping students to frame testable questions is one way for them to understand the concept of cause-effect relationships. Social Studies This is a wonderful time to connect science to the history of transportation and inventions. Students can investigate different types of transportation (land, water and air) and make 3 of 11

4 timelines displaying changes in the way we travel and how these changes have affected our lifestyles (another way to look at the big idea of cause-effect). Researching particular periods in history can yield interesting discussions about the similarities and differences in the concepts behind evolving modes of travel. (For example, the bicycle used the concept of a saddle as in riding a horse but drew variables from other modes for other parts of the design.) Language Arts/Poetry Motion poems are an interesting way to review nouns and verbs. Following a simple noun-verb formula to begin with - for example, cars drive, planes fly, people walk students can write and illustrate poetry describing all the many types of movement they observe in the world. Students might be introduced to using a dictionary or thesaurus to find some of the more unusual or hardto-spell verbs. These poems can also be compiled into a published class book to donate to the school library or to give to classes of younger students to read. Reading Reading informational (nonfiction) books about types of transportation or about scientists who worked with the concept of motion and forces, such as Newton, can expand students knowledge. Students can then write about what they learned or present what they learned to their classmates. Math I usually teach measurement along with the motion unit because it is so important to the investigations that we do. There are many problems relating to measurement that students can solve. One that we have done was to investigate the distance Orville Wright flew his first time flying (118 feet) and how far we thought that was from our classroom. Students can also get experience with metric and standard measurements and their appropriate abbreviations. (As a scientist communicating with scientists all over the world, they would need to use metric, not standard, measurements.) Teaching Tips and Guiding Questions Although I would hope that both boys and girls have had some prior experiences with racing toy cars, I have learned not to assume anything about students prior experiences. Many cub scouts may have already been involved with building pinewood derby cars and be quite adept at understanding some of the underlying concepts. I d allow a bit of time for some exploratory play (disguised as a get to know a little about your car" activity) before beginning. Here are some guiding questions I might ask before, during and after the students investigations: Which variable do you think will affect distance the most? Do you have a reason for this prediction? (past experiences) How can you prove (or disprove) your prediction? How will set up your investigation? What materials will you need? What happens if you add more than one weight to your car? What happens if you add three weights? What happens if you make your tracks steeper? less steep? (Don t forget to be sure it is still stable.) 4 of 11

5 What happens when you add more track to your existing track? Why do you think the car went farther when you did this? Can you tell me which result shows the best distance and explain why? Can someone else understand your explanation? Did you test more than once? Was there a difference in your results? Do you notice any patterns in your results? I also find that using examples of student work at the Expert and Practitioner levels helps other students to see clear models of expected performance. Concepts to be Assessed (Unifying concepts/big ideas and science concepts to be assessed using the Science Exemplars Rubric under the criterion: Science Concepts and Related Content) Physical Science Motion and Forces: Students observe that mass, gravity and surface, when applied to objects, can affect the distance traveled by the object, that unbalanced forces cause changes in the speed or direction of an object s motion and that changes in an object s speed, distance traveled or direction are a result of forces acting upon it. Mathematics: Students use precise measurements. Students collect, organize and analyze data and use graphs, tables and representations appropriately. Skills to be Developed (Science process skills to be assessed using the Science Exemplars Rubric under the criteria: Scientific Procedures and Reasoning Strategies, and Scientific Communication Using Data) Scientific Method: Predicting, planning and carrying out an investigation, recording results and drawing conclusions. This is also an opportunity for setting up a fair test by identifying and controlling variables. Other Science Standards and Concepts Addressed Scientific Method: Students predict, observe, investigate and explain phenomena. Students design a fair test, collect data and analyze the data to draw conclusions. Students use evidence to construct an explanation based on these observations and the concepts learned. Mathematics (Measuring) and Technology: Students understand that the proper use of measuring tools is important to scientific inquiry and drawing conclusions. Physical Science Forces and Motion: Students apply forces (inertia, gravity and friction) to objects and observe the objects in motion. Students explain that unbalanced forces cause changes in the speed or direction of an object s motion, that when no external force is acting upon it a body at rest remains at rest, and that a body in motion continues in motion (inertia). Students understand the mass of a body is a measure of its inertia. 5 of 11

6 Suggested Materials Materials for this inquiry are simple: a large number of Hot Wheels tracks and toy cars (I usually send home a letter asking to borrow these items); clay, washers or other easily attachable items for weight; rulers, tape measures or yard/meter sticks; and recording sheets for the results. (An alternative to tracks might be to build ramps, but extending ramps is not as easy as it will be with track pieces that snap together and are flexible.) Other rolling objects (e.g., Lego cars) might also be substituted, as long as adjustments to weight can be made to them. Possible Solutions The solutions will depend on which variable the student investigated. Distance is affected by each of the three variables in different ways. Typically, the steeper the track, the farther the car will go. Adding lengths of track, as long as the surface is smooth (which reduces friction), will also enable the care to go farther. The variable of weight is more complicated: too much weight will slow the car down, and very little weight will have no real effect on distance. Students testing this variable should be able to state, based on their investigation, how much weight is optimal for getting the greatest distance. Task-Specific Assessment Notes Novice The student shows no evidence of planning or using a strategy to carry out the investigation successfully. The student tests two variables at the same time (e.g., height of ramp and weight) but the conclusion given refers only to one variable. The drawing is not labeled or explained very well. Results recorded are incomplete, and there is no reference to which variable was being tested to get these results. No measurement of distance is included, and it is unclear whether the student used tools to measure and verify conclusions. There is some understanding of the effect of weight on distance, but it is difficult to tell how this student came to that understanding. Apprentice The student uses some planning in the investigation, but does not complete the investigation successfully. An attempt is made to describe the procedures used and how variables will be controlled. Data include two trials and measurements with units. The results found are not accurate, as the student has difficulty using a tape measure and not enough trials were done to draw an accurate conclusion. (The student does not find an optimum weight to add and concludes that more weight will always reduce distance.) The drawing is unlabeled and unclear as to how it relates to conducting the investigation. The conclusion given relates to the variable used and demonstrates some understanding of the concept, but further explanation and testing are needed to verify results. 6 of 11

7 Practitioner The student effectively explains and uses a strategy that leads to successful completion of the task, which answers the question being investigated. All relevant information is included and the steps followed are clear, but visual representation is lacks labels and details. Data include the number of trials and measurements taken, with appropriate units. The student shows good understanding of what a variable is and of how to conduct a fair test by changing only one variable at a time. The results recorded support what was in the conclusion. Note: Simple graphing of the results of several trials might help students to see patterns emerging. I might select a few Practitioner examples for the class to graph together and discuss patterns in the data. Expert The student effectively explains how the investigation was planned and carried out. The steps followed are clear and detailed. The visual representation is labeled and reflects the process used to answer the question. Data include the number of trials and measurements taken, with appropriate units. The student shows good understanding of what a variable is and how to conduct a fair test by changing only one variable at a time. Results are precise, accurate and well organized. The conclusion demonstrates an interpretation of the results that extends understanding of the concept of friction (although trials three and four were the same, trial five increased distance). The student is able to make the connection between friction and distance. The student also poses a new question for investigation as a result of this task (testing steepness). Note: The Expert's drawing is so clear that the reader can interpret what was done during the inquiry. I d use this (and some less detailed drawings) without the other supporting explanations to demonstrate to students how the labeled drawing enhances the lab report. I d ask, Can you tell from just the labeled drawing what the investigator did? (You can identify variable tested, number of trials, and materials used.) 7 of 11

8 Novice 8 of 11

9 Apprentice 9 of 11

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11 Expert 11 of 11