Notes

The concepts of velocity and acceleration are often confused by beginning students of physics. This confusion will inevitably surface during a study of 1-dimensional free-fall motion. Students can often successfully solve free-fall problems while their conceptual understanding of the motion is rather thin. This Up and Down Concept Builder will put student understanding regarding these concepts to the test. It makes for an awesome formative assessment of student understanding of velocity and acceleration concepts in the context of a free-fall motion.

In this activty, students will do the following:

• Identify the direction of the velocity and the acceleration vector at several points within the up-and-down trajectory. (Activity 1)
• Make comparisons of the relative magnitude of the velocity and acceleration for three points in the up-and-down trajectory. (Activity 1)
• Use an understanding of velocity and acceleration values and direction to identify the proper vector diagram for three locations within a trajectory if given the vector diagram at a fourth location. (Activity 2)
• Identify the numerical values of velocity and acceleration at 1-second intervals over the course of a 6-second and an 8-second trajectory. (Activity 3)

There are three activities in this Concept Builder. In order to complete an activity, a student must correctly analyze each situation at that level. If a student's answer is incorrect, then the student will have to correctly answer the same or very similar question twice in order to successfully complete the activity. This approach provides the student extra practice on situations for which they exhibited difficulty. As a student progresses through an activity, a system of stars and other indicators are used to indicate progress on the activity. A star is an indicator of correctly analyzing the situation. Once a star is earned, that situation is removed from the cue of situations to be analyzed. Each situation is color-coded with either a yellow or a red box. A red box indicates that the student has incorrectly analyzed the situation and will have to correctly analyze it twice before earning a star. A yellow box is an indicator that the situation must be correctly analyzed one time in order to earn a star. Once every situation for an activity has been successfully analyzed, the student earns a medal that is displayed on the Main Menu. This system of stars and medals allows a teacher to easily check-off student progress or offer credit for completing assigned levels.

This Concept Builder is intended for use in the middle stages of a learning cycle on free fall motion. Teachers using the Concept Builder with their classes should preview the activity (or view the Questions in the separate file) in order to judge the appropriateness of each of the three activities for their classes. We recognize that there are some physics courses that will delve no deeper into the mathematics of a free fall than is done in this Concept Builder. Yet, intensive problem-solving is not the end goal for some courses. Such conceptual-style Physics courses often use -10 m/s/s for the value of gravitational acceleration. This option is provided in the Concept Builder. The -9.8 m/s/s is the other option. Teahcers will have to decide on which value they wish their students to use and inform them in advance.

We believe that the most valuable (and most overlooked) aspect of this concept-building activity (and any of our Concept Builders) is the Help Me! feature. Each of the three tasks is accompanied by a Help page that discusses the details of completing that task. 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.