Notes:

The Free Fall Concept Builder is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Concept Builder can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

Teaching Ideas and Suggestions:

This Concept Builder targets the concepts of velocity and acceleration for a free-falling object. To be successful, students must understand the distinction between velocity and accelration. Velocity is a speed with a direction; it indicates how fast an object is moving and in what direction. Students must indicate the speed and velocity direction at various locations along the trajectory of a vertically-launched projectile. And they must understand that the velocity is decreasing as the object rises towards its highest point, that it is descreasing as the object falls from its highest point, and that it is 0 m/s at its highest point.

To be successful with this Concept Builder, students must also undestand that a free-falling object accelerates downward at approximately 10 m/s/s (more precisely, 9.8 m/s/s). This acceleration is always directed down (the meaning of the "-" on -9.8 m/s/s). And this acceleration has an unchanging value. For every second of motion, there is 10 m/s change in speed. This constancy of acceleration allows a student to predict the speed at any time if the initial speed or the speed at any other time is known. It is this type of thinking that a student must do in the second and third activity of this Concept Builder.

This Concept Builder was intended as an in-class activity. The Concept Builder includes 18 different Question Groups (with 43 questions in all) organized into three different activities. Teachers using the Concept Builder with their classes should preview the activity (or view the Questions in the separate file) in order to judge which activities would be most appropriate for their students. Our summary of the three activities is as follows:

• Describing Free Fall: Includes Question Groups 1-6; students must identify the direction of velocity and acceleration and be able to describe these quantities as increasing, decreasing, or remaining constant at during various parts of the trajectory of a vertically-launched object.
• Speedometer: Includes Question Groups 7-12; if given the initial launch velocity of a vertically-launched object, students must identify the time at which the object would have a specified speed and direction.
• It's About Time: Includes Question Groups 13-18; if given the speed and direction of a vertically-launched object, students must identify the time at which the object would have a specified speed and direction.

In order to complete an activity, a student must correctly analyze each situation for that activity. If a student's analysis is incorrect, then the student will have to correctly analyze the same or very similar situation 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 a level, a system of stars and other indicators are used to indicate progress on the level. 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 at a level has been analyzed, the student earns a Trophy that is displayed on the Main Menu. This system of stars and Trophies allows a teacher to easily check-off student progress or offer credit for completing assigned activities.

The most valuable (and most overlooked) aspect of this concept-building activity 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.

Related Resources

There are numerous resources at The Physics Classroom website that serve as very complementary supports for this Free Fall Concept Builder. These include:
• Curriculum/Practice: Several Concept Development worksheets at the Curriculum Corner will be very useful in assisting students in cultivating their understanding, most notably ...

Free Fall

Visit the Curriculum Corner - Kinematics.

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