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Reviewed by: Leslie Pitman (Springdale, AR) on 4/18/2022 3:54:21 PM
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This is an online simulation in which spheres of varying masses are “hit” with varying amounts of force, and the resulting accelerations are displayed in table format. Students are asked to come up with a rule to explain the relationship between mass, force and acceleration. To see the instructions, find the word “instructions” (slightly buried in the data table itself) and mouse over it.
MS-PS2-2 Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object. Clarification Statement: Emphasis is on balanced (Newton’s First Law) and unbalanced forces in a system, qualitative comparisons of forces, mass and changes in motion (Newton’s Second Law), frame of reference, and specification of units. Assessment Boundary: Assessment is limited to forces and changes in motion in one-dimension in an inertial reference frame and to change in one variable at a time. Assessment does not include the use of trigonometry.
This resource is explicitly designed to build towards this performance expectation.
Comments about Including the Performance Expectation This simulation allows students to collect evidence showing how acceleration changes as the force (just one force) on an object changes, and as the mass of that object changes. Students will already need to be familiar with the word “acceleration” as a change in motion. The data table format in which information is displayed is helpful for students to pick out patterns that they can use to derive a qualitative relationship between mass and acceleration, and between force and acceleration. The activity is useful as an introduction to the Performance Indicator and its concepts, not as a culminating activity. It should be followed in the classroom by other lessons in which more than one force is involved, and lessons in which students can design and run their own investigations.A teacher can also address the idea about “the sum of the forces” by using the phrase “net force”, e.g. pointing out that the ball at rest has a net force of zero.
This resource is explicitly designed to build towards this science and engineering practice.
Comments about Including the Science and Engineering Practice Students are asked to construct an explanation (“write a rule”) about how mass, force and acceleration are related. The simulation can be used entirely to describe phenomena, or students can be asked to use partial data to predict “missing” information, as described in the Tips for the Practice of Analyzing and Interpreting data, above. The simulation could be accompanied by a real-life phenomenon, to clarify the jump from specific model to general explanation. The data provided is quantitative, though units of measurement are not provided. The underlying math seems to be a straightforward F=ma, so if a teacher wishes to incorporate units, it may be inferred that these are Newtons, kg, and m/s2 respectively. Students are most likely to describe the relationship as a = F/m, so if a teacher or curriculum presents Newton’s Second Law as F = m x a, the teacher will need to make sure it is clear to all students that the two expressions are in fact the same.
Comments about Including the Science and Engineering Practice Students are asked to used the data from the completed chart to write a rule about how mass, force and acceleration are related. If done as a whole-class activity (projected onto a screen that all can see), students can request certain combinations of force and acceleration, and once a few points are filled in on the data table, students can be asked to analyze the data they have in order to make predictions about what the acceleration will be when certain other combinations are used. Predictions can be shared via whiteboard, worksheets, or discussion. Students can be asked to explain the reasoning behind their predictions. A teacher could ask students to graph the data to determine if the relationships are linear.
This resource is explicitly designed to build towards this disciplinary core idea.
Comments about Including the Disciplinary Core Idea The simulation’s data table does not include a row for zero net force, but it’s quick enough for a teacher to ask the students what the ball does when no force is being applied from the launcher. The simulation and data table directly illustrate that larger forces create larger changes in motion, and that as force increases on a mass, the acceleration increases. To really emphasize the idea that to get the same acceleration with a larger mass, more force is needed, a teacher could ask students “are any of the filled-in accelerations the same? What do you notice about the conditions that make the same accelerations happen?”.
This resource is explicitly designed to build towards this crosscutting concept.
Comments about Including the Crosscutting Concept The students are asked to come up with a rule about the relationship between the variables. The patterns they observe in the data table are the foundation for that rule. Without other instructions, some students’ rules will likely be descriptions of the patterns they observe, e.g. “When the force is 1, the number on the bottom of the fraction of acceleration gets one bigger each time - 1/1, ½, ?, ¼, then ?”, while other students’ rules will use those patterns to come up with a mathematical rule, e.g. “The acceleration is the force divided by the mass”. Students can be encouraged to make predictions about what the acceleration will be with certain combinations of mass and force, and can be specifically reminded that they can make those predictions based either on a hypothesis about relationships, or by filling in a pattern they see in the existing data surrounding the “hole” in the chart.