cord of the yoyo. But point-tracking makes the measurement at hand easier and less
time-consuming: in the starting frame, the positions of the hand and of the sticker are
specified and the shapes of the search areas (white boxes) are set, and then the
coordinates of these points are automatically recorded in subsequent frames.
In the diagram to the right, the horizontal position and the vertical position of P1
are plotted against time. This is combined in the diagram with a sinusoidal fit of the
horizontal displacement of the yoyo, due to an unintentional pendulum motion of the
yoyo, and a quadratic function fit of the vertical position during the first phase in
which the yoyo unwinds. These trend curves can be used as coordinate functions of a
computed point that is displayed in the video clip (P2): It turns out to be close to the
position of the axle during the unwinding phase of the yoyo. Please refer to Heck and
Uylings (2005) for detailed modelling of the yoyo motion.
12.4.2.3 Educational Benefits
The Coach tool for video measurement has much added value if it is incorporated
appropriately in school science. First, like the data-logging tool, video measurement
creates new possibilities and contexts for experimentation activities. With the videomeasurement tool, the teacher can bring real-life, attractive scenes of motion into
classroom activities that show pupils the relevance of science concepts and theory in
everyday life (Heck 2009; Zollman and Fuller 1994). Such realistic scenes of motion
can be quite ordinary (e.g. basketball shots, amusement-park rides, dancing) or
unusual (e.g. car crashes, jumps on the Moon, rocket launch). With high-speed
videos (i.e. up to 1200 frames/s), the teacher and pupils can quantitatively explore
many more situations of realistic motions (e.g. multidimensional collisions between
billiard balls, gun recoil) that would be mostly impossible to investigate with
traditional instruments and even with sensors for school science. Additionally, the
video-measurement tool can serve as a cost and time effective instrument for the
school laboratory, which might replace rulers, timers, photogates and motion sensors
in motion-related experiments.
Second, the tool enables the collection and representation of many video data
from different realistic situations in a short time (physical world). Consequently,
pupils will have time in the classroom to interpret data and/or explain relationships
(theoretical world). Third, the “real-time graphing” and “scan” features of the videomeasurement tool stimulate pupils to think back and forth between the physical and
theoretical worlds. This becomes more likely as images of these two worlds are
shown in the same software interface (Fig. 12.3). When pupils scan a data point in
one of the graphs, the corresponding video frame, where the data were collected,
displays simultaneously. This feature enables pupils to identify events during the
realistic situation (physical world) and connect them to abstract representations in
the graph (theoretical world). This results in pupils’ deeper understanding of the
motion and related kinematic concepts (Beichner 1996; Gröber et al. 2014).
Finally, the incorporation of the video-measurement tool makes it possible for
pupils to exercise experimental inquiry practices like those of biomechanics and
12 Stem, Inquiry Practices and Technology in Physics Education
137
time-consuming: in the starting frame, the positions of the hand and of the sticker are
specified and the shapes of the search areas (white boxes) are set, and then the
coordinates of these points are automatically recorded in subsequent frames.
In the diagram to the right, the horizontal position and the vertical position of P1
are plotted against time. This is combined in the diagram with a sinusoidal fit of the
horizontal displacement of the yoyo, due to an unintentional pendulum motion of the
yoyo, and a quadratic function fit of the vertical position during the first phase in
which the yoyo unwinds. These trend curves can be used as coordinate functions of a
computed point that is displayed in the video clip (P2): It turns out to be close to the
position of the axle during the unwinding phase of the yoyo. Please refer to Heck and
Uylings (2005) for detailed modelling of the yoyo motion.
12.4.2.3 Educational Benefits
The Coach tool for video measurement has much added value if it is incorporated
appropriately in school science. First, like the data-logging tool, video measurement
creates new possibilities and contexts for experimentation activities. With the videomeasurement tool, the teacher can bring real-life, attractive scenes of motion into
classroom activities that show pupils the relevance of science concepts and theory in
everyday life (Heck 2009; Zollman and Fuller 1994). Such realistic scenes of motion
can be quite ordinary (e.g. basketball shots, amusement-park rides, dancing) or
unusual (e.g. car crashes, jumps on the Moon, rocket launch). With high-speed
videos (i.e. up to 1200 frames/s), the teacher and pupils can quantitatively explore
many more situations of realistic motions (e.g. multidimensional collisions between
billiard balls, gun recoil) that would be mostly impossible to investigate with
traditional instruments and even with sensors for school science. Additionally, the
video-measurement tool can serve as a cost and time effective instrument for the
school laboratory, which might replace rulers, timers, photogates and motion sensors
in motion-related experiments.
Second, the tool enables the collection and representation of many video data
from different realistic situations in a short time (physical world). Consequently,
pupils will have time in the classroom to interpret data and/or explain relationships
(theoretical world). Third, the “real-time graphing” and “scan” features of the videomeasurement tool stimulate pupils to think back and forth between the physical and
theoretical worlds. This becomes more likely as images of these two worlds are
shown in the same software interface (Fig. 12.3). When pupils scan a data point in
one of the graphs, the corresponding video frame, where the data were collected,
displays simultaneously. This feature enables pupils to identify events during the
realistic situation (physical world) and connect them to abstract representations in
the graph (theoretical world). This results in pupils’ deeper understanding of the
motion and related kinematic concepts (Beichner 1996; Gröber et al. 2014).
Finally, the incorporation of the video-measurement tool makes it possible for
pupils to exercise experimental inquiry practices like those of biomechanics and
12 Stem, Inquiry Practices and Technology in Physics Education
137