Notes

This Concept Builder is intended for use near the early stages of a learning cycle on Kinematic description of motion. The use of motion diagrams has become more common in the past couple of decades, in part due to the influence of the Physics Modeling curriculum. A motion diagram includes both a dot diagram (sometimes referred to as a ticker tape diagram or an oil drop diagram) and a set of vectors that display either the velocity, the acceleration, or both over the course of the object's motion. The construction of such a motion diagram demands that the learner have a strong conceptual understanding of position, velocity, and acceleration.

This Concept Builder is divided into three activities - Dot Diagrams with Velocity Vectors (Activity 1), Dot Diagrams with Acceleration Vectors (Activity 2), and Motion Diagram Challenges (Activity 3). Each activity presents the learner with six verbal descriptions of an object's motion; the learner must create the correct motion diagram for each. The six verbal descriptions include two constant speed motions (one for moving to the right and one for moving to the left), two speeding up motions (one for moving to the right and one for moving to the left), two speeding up motions), and two slowing down motions (one for moving to the right and one for moving to the left), two speeding up motions). We encourage teachers to view the questions on the Questions Page.

In Activities 1 and 2, the learner is given immediate feedback after every decision that is made. If the learner's decision is incorrect, they are provided an immediate opportunity to correct it. This continues until the correct decision regarding a dot diagram or a set of vectors is made. In this sense, one can be assured that eventually the learner will complete Activity 1 and Activity 2. Activity 3 is quite different and serves more of the function of a quiz or formative assessment. The learner must make all the decisions regarding the dot pattern, the set of velocity vetors, and the set of acceleration vectors before the answer is checked. When checked, an incorrect answer cannot be immediately corrected. The learner will instead have to answer two nearly identical questions correctly before mastery of that question is achieved. This approach provides learners with the most practice on the questions that they miss.
 

This Concept Builder was intended as an in-class activity. After some discussion and practice with motion diagrams and the inter-relationship of position, velocity, and acceleration, the Concept Builder can be used. It is adviseable to not underestimate the difficulty of this task, particularly the third activity. Leaners will need to understand the distinction between velocity and acceleration. And they will particularly need to understand the concept of a constant acceleration. Emphasize that accelerating objects are changing their velocity. And emphasize that if the camount of change in the velocity is the same amount every second, then the acceleration value is a constant value. On a motion diagram, this constant acceleration is represented by an acceleration vector that doesn't change in length. There are numerous ways to represent this concept of a constant acceleration; a popular method tends to be the use of a velocity-time table or a velocity-time graph. Displaying a column of times that iterate by 1.0 seconds from one row to the next and a column of velocities that are changing, but always changing by the same amount. When students see the numerical representation of a velocity that is changing with a change amount being the same from one second to the next, they more easily latch onto this concept of a constant or uniform acceleration. A few such example tables make for a great pre-cursor to this Concept Builder.

The most valuable (and most overlooked) aspect of this Concept Builder is the Help Me! feature. Each question group is accompanied by a Help page that discusses the specifics of the question. This Help feature transforms the activity from a question-answering activity into a concept-building activity. The student who takes the time to use the Help pages can be transformed from a guesser to a learner and from an unsure student to a confident student. The "meat and potatoes" of the Help pages are in the sections titled "How to Think About This Situation:" Students need to be encouraged by teachers to use the Help Me! button and to read this section of the page. A student that takes time to reflect upon how they are answering the question and how an expert would think about the situation can transform their naivete into expertise.

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Motion Diagrams Concept Builder. These include:

Additional resources and ideas for incorporating Motion Diagrams into an instructional unit on Kinematics can be found at the Teacher Toolkits section of The Physics Classroom website. Visit Teacher Toolkits.