Before: (Days 1-3)
The teacher will introduce the lesson by showing multiple failed snow sledding attempts with a variety of variables in each attempt such as the type of sled, the number and size of people, the slope of hill, etc. See Snow Sledding FAILS & Wipeout Compilation.
The teacher will define the vocabulary words:
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force-strength or power exerted upon an object
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balanced-equal distribution of weight
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unbalanced-unequal distribution of weight
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variable-something that may or does change
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size-the spatial dimensions, proportions, magnitude, or bulk of anything
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direction-the line along which anything lies, faces, moves, etc.
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speed-how fast or slow an object is moving (equation: speed = distance/time)
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position-condition with reference to place; location; situation.
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friction-surface resistance to relative motion, as of a body sliding or rolling
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air resistance-the opposition of the atmosphere to forward movement
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The students will make flashcards to study the ten terms listed above to be incorporated into their discussions and reflections about manipulating the variables to create the longest snow sled ride.
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The teacher will guide a class discussion about the students' previous experiences with snow sledding, being at the top of a wave on a bodyboard, trying to catch a wave, riding down a hill on a bike, or peddling uphill.
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The teacher will explain to the students that many variables influenced the ease or the struggle of these events.
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The teacher will present balanced and unbalanced forces using marbles and a balance scale.
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When balanced forces act on an object at rest, the object will not move. If the force pushing back is equal, then there will be no movement. To be equal means to be balanced. For example, watch as I (the teacher) put one marble on both sides of the balance scale. The students will observe that the scale is balanced, or equal, and one side is not lower or higher than the other. The teacher will inform students that as long as both sides only have one marble, they are balanced, or equal, and neither side of the balance scale will move.
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Forces that cause a change in the motion of an object are unbalanced forces. To be unbalanced means to be unequal. For example, watch as I (the teacher) add only one marble to either side of the balance scale. The students will observe that the scale becomes unbalanced, or unequal as one side (the side with two marbles) becomes lower. The teacher will inform students that as one marble is added to the other side of the balance scale (the one with only one), the scale becomes balanced or equal again. The teacher will ask, “What happens if I add only one marble to both sides again?" (both sides will have an equal amount). "What happens if I only add one to one side of the balance scale again?"(one side becomes unequal or unbalanced again).
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The teacher will explain to the students that they will soon begin to evaluate the variables such as balanced and unbalanced forces that cause a snow sled to slide down a teacher-created hill and either allow or not allow it to be the longest snow sled ride.
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The teacher will explain that the students will also design their own snow sled based on their knowledge of the terms and relative past experiences, and what they hypothesize (claim) would be a better way to get a longer ride on a snow sled.
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The students will take “silent wait time” (10-30 seconds) to think about what may cause the snow sled ride to end so soon in the video Snow Sledding FAILS & Wipeout Compilation.
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Next, the students will write their idea about the variables that would create the optimal snow sled on a Post-it note.
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The students will then turn and talk to their elbow partners about what they wrote on their Post-it note.
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The teacher will listen in on student elbow partner (student to the left or right of the student) conversations and will be sure to acknowledge on-task thinking, unique ideas, and incorporation of vocabulary taught.
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The teacher will prompt students in peer discussions if any students appear to be off task or have trouble conveying ideas.
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Finally, the teacher will choose a couple of Post-it notes per table and write the students' ideas on chart paper. The teacher will use this to model writing a hypothesis, or claim, as to what snow sled construction would lead to the longest snow sled ride. For example, the teacher may write, “A snow sled made of popsicle sticks and tape would make for the longest snow sled ride. The popsicle stick sled will hold three marbles in the foam cup."
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Students will be assigned to strategically organized groups (3-4 students consisting of high, average. and low ability students) by the teacher.
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Students will meet with their groups and write the hypothesis or claim in their journals for snow sled that would result in the longest snow sled ride.
During: (Days 4-7)
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Students will use the internet to access the links How to make a popsicle snow sled, Top Five Snow Sleds , Homemade sled for 8 dollars with Chromebooks, or portable devices (such as tablets) to begin researching their ideas on how they will design and construct a scaled model of a snow sled to test.
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The teacher will facilitate with the research process as needed to ensure all students are on task and using internet access appropriately.
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Students will review the supplies and determine the materials to be used in construction with their groups.
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Students will collaborate with their groups to draw a design of the snow sled they are constructing and begin to prepare and/or modify materials they will be using to construct their snow sled.
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The suggested snow sled supply materials are as follows: bucket or small plastic bin, plastic bowl, paper bowl, plastic dessert plate, paper dessert plate, frisbee, tin foil (options for sled foundation), scotch tape, ruler, paper, string, Legos, marbles, popsicle sticks, and foam cups. Students will not be required to use all materials but will not diverge from the list of offered material for the initial test of their initial snow sled design and construction.
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The students will use the group design to guide the construction process.
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To build the snow sled, the students will utilize their supplies and build a snow sled that will be released from the same point three times from the marked top of the scaled hill.
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The teacher can use any size or construction of the ramp to test all snow slides for each group.
Keep in mind that all students' snow sleds will be tested on the same ramp. A simple way to create a ramp is to:
- Clear a space about 10 feet long--this will be the runway.
- Stack two or three thick textbooks books at one end of the runway.
- Lean one end of a wooden board on the books and place the other end on the floor.
The teacher will facilitate as students begin the process of testing and documenting the time and distance of each of their snow sled rides. The teacher will use tape and a marker or group color assigned sticky dots to mark the stopping point of each snow sled test. Each group attempt should be labeled with a 1, 2, and 3 to indicate which ride was the longest.
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One person from each group will take time measurements. A ruler will be used to measure the distance from the release point to the stopping point of the snow sled ride.
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One person from each group will place their sled at the top of the ramp.
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One student from the group will release the snow sled without pushing it.
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One student from the group will use the stopwatch. The watch should be started at the exact same moment the snow sled is released.
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Each group will complete this process a total of three times being sure to document the time and distance in their journals. Students may manipulate one variable at a time (for example adding or taking away marbles) between each snow sled test. At this point, it is important to note any of the snow sleds that are turning over, sliding off the ramp, or having any other issues that cause an unbalance force to act upon the snow sled. Students must document that a variable was changed before it is tested.
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The teacher will ensure that students are collecting at least sixes pieces of data (3 for speed and 3 for distance), and that they are organized by each test.
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The teacher will be sure that students document changing variables (for example adding or taking away marbles) between each snow sled test. Again, it is important to note any of the snow sleds that are turning over, sliding off the ramp, or having any other issues that cause an unbalanced force to act upon the snow sled. The teacher will discuss the positive effects of an unbalanced force such as, 5 properly placed marbles can cause the sled to go faster than 5 improperly placed marbles.
After: (Days 8-10)
- The teacher will introduce the Optimal Snow Sled Experience Presentation Rubric, so that each student is aware of what will be required in the group presentation. The teacher will clear up any misconceptions or answer any questions regarding the rubric.
- Students will then chart their data graphically (teacher choice as to how this will be displayed eg: bar graph, T-chart, etc.)
- Students will then observe which of their snow sled attempts was the longest snow sled ride.
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The teacher will ensure students note which unbalanced and balanced forces influenced each snow sled attempt.
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The teacher will ensure students are evaluating their snow sled design and discussing how variables can be manipulated to improve the snow sled distance and time.
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Each group will then work to create a display and present a group chart of the data collected for each of the three release points. (Chart paper or a multimedia slide presentation, such as Google Slides, can be used. Google Slides will require prior access and sign up with Google, which is free. This program is one of the easiest to navigate for beginning learners, and best for easy access, use, and presentation. Groups can work together on the presentation by assigning certain slides through a shared document or the teacher may choose to allow groups to work from one group computer).
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The teacher will facilitate the class discussion about which group had the longest snow sled ride.
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The teacher will facilitate as students draw the connection between manipulating balanced and unbalanced forces to cause the ride to be longer. For example, 5 marbles would cause more of an unbalance than 0. Five marbles can cause the sled to go faster down the ramp. The unbalanced force guides the snow sled down the hill. As the sled reaches the bottom the marbles scatter out and off the sled, the force becomes balanced again, and the sled stops.
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