Mixed-Reality Demonstrations Involving Gravity
CONNECTED CL ASSROOM
Mixed-reality science labs combine hands-on activities with computer augmentation or simulation. This
provides the rich context and multisensory
experience of hands-on activities with visualizations of processes that otherwise would not be
visible.
The University of Virginia Center for Technology and Teacher Education is collaborating with
the Concord Consortium on a number of mixed-reality activities ( concord.org/projects/mixed-reality-labs) in physics and chemistry. In one
activity, pressing a plunger connected to a tablet
computer provides a visualization that shows
air molecules compressing as the plunger is depressed. Force feedback causes the force required
to depress the plunger to increase as the gas
molecules in the visualization are compressed.
The physical elements of a mixed-reality demonstration provide a conceptual anchor, known
as a concept image, that makes it easier to understand an abstract concept. For example, teachers
often use a ball-drop activity to help students
understand acceleration due to gravity. Students
drop a ball and measure its position at a series of
points in time. You can use a variety of mixed-reality methods to accomplish this.
We printed a metric ruler on a sheet of paper
and then taped together a series of overlapping
sheets to create a single ruler 200 centimeters
long. We used this as a backdrop while video-recording a ball falling at 30 frames per second
(a standard rate for video).
During playback, we measured the position
of the ball at every third frame. This established
the position of the ball at intervals one-tenth of
a second apart. We then used this information to
transfer the position of the ball to another strip
of paper, shown in the image to the right.
We used this strip of paper to initially explore
the relationships involved without numbers to
make the concept more accessible to students
who are uncomfortable with numerical methods.
By cutting the paper apart at the marks, you can
line up a series of strips (shown in the image at the
Top left: A video recording a ball as it drops can help
students visualize math concepts.
Bottom left: The white strips show that a ball's speed
increases as it falls. The blue strips show that the rate of
increase from one time interval to the next is constant.
Right: The numbered strip illustrates that a falling ball
travels farther with each successive time interval.
