Student+Understanding+-+Evidence

[|Student Understanding Spreadsheet]





Below is from diagnoser.com: Facets and facet clusters are a framework for organizing the research on student conceptions so that they are understandable to both discipline experts and teachers. Facet clusters include the explicit learning goals in addition to various sorts of reasoning, conceptual, and procedural difﬁculties. Each cluster contains the intuitive ideas students have as they move toward scientiﬁcally accurate learning targets. Facets are arranged with the Goal Facets at the top of the page followed by the more problematic facets. Each facet has a two-digit number. The 0X and 1X facets are the learning targets. The facets that begin with the numbers 2X through 9X indicate ideas that have more problematic aspects. In general, the higher facet numbers (e.g., 9X, 8X, 7X) are the more problematic facets. The X0ʼs indicate more general statements of student ideas. Often these are followed by more speciﬁc examples, which are coded X1 through X9.
 * Facet Cluster - Acceleration**

Facet Cluster 00 The student correctly identiﬁes acceleration as the rate at which the speed of an object changes including both speeding up and slowing down. --01 The student is able to compare acceleration of two or more objects by comparing the changes in speed for equal time intervals. --02 Given position vs. time information, the student correctly identiﬁes time intervals where acceleration occurs. 10 The student correctly deﬁnes and calculates acceleration as the ratio of the change in speed divided by the change in clock reading. 30 Student determines the average acceleration by applying only part of the deﬁnition of acceleration. --31 Student reports the acceleration as equaling the change in speed or just the ﬁnal speed without consideration of change in clock reading. --32 Student reports the acceleration as the ﬁnal speed divided by the ﬁnal time when the initial speed and/or initial time is not zero. 50 Student describes the acceleration as happening instantaneously, i.e., student does not consider needing a time interval for the change in motion to occur. --51 Student reports a single speed on a speed vs. time graph as the acceleration. 60 When asked for the acceleration, the student tries to determine a speed. --61 Student determines the acceleration by averaging the initial and ﬁnal speeds. --62 Student determines the acceleration by noting the change in position. 70 Student concludes that if an object has zero speed, even for an instant, it also has zero acceleration. (This instant may appear at the starting point, ending point, or a turn around point.) 80 Student confuses position vs. time and speed vs. time graphs or data tables. --81 Student interprets sloping up (or down) on a position graph to mean the object is speeding up (or slowing down). --82 Student interprets a ﬂat line segment on a position graph to mean the object is moving at constant speed. --83 Student interprets sloping up (or down) on a speed graph to mean the object is moving with constant speed away from (or toward) the origin. --84 Student interprets a ﬂat line segment on a speed graph to mean the object is not moving. 90 Student concludes that if an object has a speed, it must be accelerating. --91 Student determines if an object is speeding up or slowing down by looking at whether the object is going fast or going slow.

Notes 3/27/10: Facets 50 & 51 (5 occurrences) and 70 (4occurrences) both have multiple chances to show up (x4). If a student has 50 or 51, fewer miss it but when they miss it, they miss it consistently. Although less common, application of the misconception is consistent. If a student has 70, they miss about one or two. Sometimes they get it right, sometimes wrong. Application of the misconception is not as strong. 70 is when the velocity is zero at some point, student think there is no acceleration. This happens in 3 places, starting, stopping and turning around. We think misconception is explicitly about the turnaround case. Questions 6 and 7: students think ANY change means an acceleration.
 * 31: Quesiton 5, they are not applying the COMPLETE defintion of acceleration--seems to be common. 18% applied only the final velocity, and 36% applied only the DIFFERENCE in velocity. We should have "3" as an answer to check for 6 m/s / 2 sec.

Three trouble areas: Identifying turnaround as STILL accelerating. Anything changing means acceleration. Applying only PART of the definition of acceleration (ie. using only delta v or final velocity as calculation of acceleration.)

From followup question, "If you had to define acceleration in your own words, how would you define it?" Most students think it is JUST a change in velocity. Vast majority only mention speeding up.