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Table of contents
T
E
CBR
X
A
S
I
NS
T
R
U
)
M
E
)
N
T
)
S
I
NTRODUCTION
What is CBR? 2
Getting started with CBR — It’s as easy as 1, 2, 3 4
Hints for effective data collection 6
Activities with teacher notes and student activity sheets
TRIGGER
85-86
92
³
Activity 1 — Match the graph linear 13
³
Activity 2 — Toy car linear 17
³
Activity 3 — Pendulum sinusoidal 21
³
Activity 4 — Bouncing ball parabolic 25
³
Activity 5 — Rolling ball parabolic 29
Teacher information 33
Technical information
CBR data is stored in lists 37
RANGER settings 38
Using CBR with CBL or with CBL programs 39
Programming commands 40
statistics and data analysis: data collection methods, statistical analysis
0
What’s in this guide?
Getting Started with CBR
calculator or programming experience. It includes quick-start instructions for using
on effective data collection, and five classroom activities to explore basic functions and
properties of motion. The activities (see pages 13–32) include:
teacher notes for each activity, plus general teacher information
0
step-by-step instructions
0
a basic data collection activity appropriate for all levels
0
explorations that examine the data more closely, including what-if scenarios
0
suggestions for advanced topics appropriate for precalculus and calculus students
0
a reproducible student activity sheet with open-ended questions appropriate for a wide
0
range of grade levels
is designed to be a guide for teachers who don’t have extensive
, you’re just three simple steps from the first data sample!
CBR
Connect
Connect
using the calculator-to-
Push in
connection.
The short calculator-to-calculator
Note:
cable that comes with the calculator also
works.
to a TI graphing calculator
CBR
cable.
CBR
firmly
at both ends to make the
Transfer
RANGER
transfer the appropriate program from the
First, prepare the calculator to receive the program (see keystrokes below).
, a customized program for each calculator, is in the
to a calculator.
CBR
. It’s easy to
CBR
TI-82 or TI-83TI-85/CBL or TI-86TI-92
LINK
Ÿ
[
Next, open the pivoting head on the
program-transfer button on the
During transfer, the calculator displays
transfer is complete, the green light on
and the calculator screen displays
on
Once you’ve transferred the
won’t need to transfer it to that calculator again unless you delete it from
the calculator’s memory.
Note:
You may need to delete programs and data from the calculator. You can
save the programs and data first by transferring them to a computer using
TI-Graph Linké or to another calculator using a calculator-to-calculator cable
or the calculator-to-
flashes twice and
CBR
The program and data require approximately 17,500 bytes of memory.
For quick results, try
one of the classroomready activities in this
guide!
TI-82 or TI-83TI-85/
^
Press
Choose
Press
RANGER
›
.
.
.
^ A
Press
Choose
›
Press
or TI-86TI-92
CBL
RANGER
.
.
.
Press L [
Choose
Press ¨
VAR-LINK
RANGER
›
.
.
The opening screen is displayed.
Press
›. The
MAIN MENU
SETUPàSAMPLE
SET DEFAULTS
APPLICATIONS
PLOT MENU
TOOLS
QUIT
From the
Press
MAIN MENU
› to choose
MAIN MENU
&
&
&
&
&
choose
is displayed.
view/change the settings before sampling
change the settings to the default settings
DISTANCE MATCH, VELOCITY MATCH, BALL BOUNCE
plot options
GET CBR DATA, GET CALC DATA, STATUS, STOPàCLEAR
SET DEFAULTS
START NOW
. The
. Set up the activity, and then press › to
screen is displayed.
SETUP
begin data collection. It’s that easy!
Important information
0
This guide applies to all TI graphing calculators that can be used with
so you may find that some of the menu names do not match exactly those
on your calculator.
0
When setting up activities, ensure that the
is securely anchored and
CBR
that the cord cannot be tripped over.
0
Always exit the
RANGER
program performs a proper shutdown of
ensures that
0
Always disconnect
is properly initialized for the next time you use it.
Understanding how a sonic motion detector works can help you get better data plots. The
motion detector sends out an ultrasonic pulse and then measures how long it takes for that
pulse to return after bouncing off the closest object.
, like any sonic motion detector, measures the time interval between transmitting the
CBR
ultrasonic pulse and the first returned echo, but
much more. When the data is collected,
using a speed-of-sound calculation. Then it computes the first and second derivatives of
CBR
the distance data with respect to time to obtain velocity and acceleration data. It stores
these measurements in lists
L1, L2, L3
, and L4.
calculates the distance of the object from the
CBR
has a built-in microprocessor that does
CBR
Performing the same calculations as
Collect sample data in
➊
Use the sample times in
➋
REALTIME=NO
in conjunction with the distance data in L2 to calculate the
L1
is an interesting classroom activity.
CBR
mode. Exit the
RANGER
program.
velocity of the object at each sample time. Then compare the results to the velocity data
in
.
L3
(
+
L2
=
L3
n
Use the velocity data in L3 (or the student-calculated values) in conjunction with the
➌
sample times in
L1
n+1
to calculate the acceleration of the object at each sample time. Then
)à2 N (
L2
n
L1
n+1
N
compare the results to the acceleration data in
Object size
Using a small object at a far distance from the
+
L2
n
L1
n
decreases the chances of an accurate
CBR
L2
L4
n-1
.
)à2
reading. For example, at 5 meters, you are much more likely to detect a soccer ball than a
ping-pong ball.
Minimum range
When the
the
CBR.
be misidentified by
sends out a pulse, the pulse hits the object, bounces back, and is received by
CBR
If an object is closer than 0.5 meters (1.5 feet), consecutive pulses may overlap and
. The plot would be inaccurate, so position
CBR
at least 0.5 meters
CBR
away from the object.
Maximum range
As the pulse travels through the air, it loses its strength. After about 12 meters (6 meters on
the trip to the object and 6 meters on the trip back to the
weak to be reliably detected by the
the
G
ETTING STARTED WITH
6
. This limits the typical reliably effective distance from
beam is not a narrow, pencil-like beam, but fans out in all directions up
CBR
to 10° in a cone-shaped beam.
To avoid interference from other objects in the vicinity, try to establish a clear zone in the
path of the
recorded by
Reflective surfaces
beam. This helps ensure that objects other than the target do not get
CBR
CBR. CBR
records the closest object in the clear zone.
Some surfaces reflect pulses better than others. For example, you might see better results
with a relatively hard, smooth surfaced ball than with a tennis ball. Conversely, samples
taken in a room filled with hard, reflective surfaces are more likely to show stray data points.
Measurements of irregular surfaces (such as a toy car or a student holding a calculator while
walking) may appear uneven.
A Distance-Time plot of a nonmoving object may have small differences in the calculated
distance values. If any of these values map to a different pixel, the expected flat line may
show occasional blips. The Velocity-Time plot may appear even more jagged, because the
change in distance between any two points over time is, by definition, velocity. You may
wish to apply an appropriate degree of smoothing to the data.
program can reduce the effect of stray signals
or variations in the distance measurements. Avoid excessive smoothing. Begin with no
smoothing or
smoothing. Increase the degree of smoothing until you obtain
LIGHT
satisfactory results.
For an activity with a higher-than-average likelihood of stray signals, you may wish to
0
increase the smoothing on the
For already-collected
0
REALTIME=NO
calculator must be connected to the
choose
Noise—what is it and how do you get rid of it?
When the
SMOOTH DATA
receives signals reflected from objects other than the primary target, the plot
CBR
, and then choose the degree of smoothing.
screen before sampling (see page 38).
SETUP
data, you can apply smoothing to the data. The
. Choose
CBR
PLOT TOOLS
from the
PLOT MENU
,
shows erratic data points (noise spikes) that do not conform to the general pattern of the
plot. To minimize noise:
Make sure the
0
viewing a
REALTIME=NO
Try to sample in a clutter-free space (see the clear zone drawing on page 7).
0
Choose a larger, more reflective object or move the object closer to the
0
REALTIME=YES
is pointed directly at the target. Try adjusting the sensor head while
CBR
sample until you get good results before collecting a
sample.
CBR
(but farther
than 0.5 meters).
When using more than one
0
in a room, one group should complete a sample before
CBR
the next group begins their sample.
For a noisy
0
REALTIME=YES
obtain satisfactory results. (You cannot change the smoothing in the
VELOCITY MATCH
For a noisy
0
, or
REALTIME=NO
sample, repeat using a higher degree of smoothing until you
DISTANCE MATCH
BALL BOUNCE
applications.)
sample, you can apply a higher degree of smoothing to the
original data.
,
Speed of sound
The approximate distance to the object is calculated by assuming a nominal speed of sound.
However, actual speed of sound varies with several factors, most notably the air
temperature. For relative-motion activities, this factor is not important. For activities
requiring highly accurate measurements, a programming command can be used to specify
the ambient temperature (see pages 40–41).
when you need to collect or plot only one type of data (distance, velocity, or acceleration)
0
mode:
for a sample
In
REALTIME=YES
mode, the
processes the requested plot data (distance, velocity, or
CBR
acceleration), which is transferred to the calculator following each individual distance
measurement. Then
RANGER
plots a single pixel for that pulse.
Because all of these operations must be completed before the next sample can be
requested, the maximum rate at which data can be sampled in
REALTIME=YES
mode is
limited.
It takes approximately 0.080 seconds just to sample, process, and transfer the data for a
single data point. Additional time is required for operations such as plotting the point, which
slows the effective sample rate to approximately 0.125 seconds in
REALTIME=NO
Use
REALTIME=NO
for faster objects
0
when smoothing is required (see page 9)
0
to operate the
0
when you need to collect or plot all types of data (distance, velocity, and acceleration) for
0
mode:
in detached mode (see page 11)
CBR
RANGER
.
a sample
In
after all sampling is completed. The sample rate can be as fast as once every 0.005 seconds
for close objects. Data for time, distance, velocity, and acceleration is transferred to the
calculator.
Because the data is stored in the
and again.
0
0
0
G
ETTING STARTED WITH
10
REALTIME=NO
mode, data is stored in the
, you can transfer it from the
CBR
Each time you change smoothing, the
CBR
and not transferred to the calculator until
CBR
to a calculator again
CBR
applies the new smoothing factor, transfers
the adjusted data to the calculator, and stores the smoothed values in the lists.
Choosing a domain changes the lists stored in the calculator. If you need to, you can
recover the original data from the
choose
TOOLS
. From the
menu, choose
TOOLS
. From the
CBR
MAIN MENU
GET CBR DATA
in the
.
RANGER
program,
You also can share the same data with many students, even if they are using different
types of TI graphing calculators. This allows all students to participate in data analysis
activities using the same data (see page 11).
, you can explore the data in relationship
to a function. Because the data is collected as lists and displayed as a statistical plot, you can
use
, , and œ to explore this relationship.
Inside RANGER
Explore plots using
0
, which is set automatically. (On the TI-85, use the free-moving
TRACE
cursor.)
Manipulate the data set, including smoothing the data or selecting the domain of
0
interest.
Outside RANGER
Explore data using the calculator’s list editor.
0
Manually model a function to the data using the calculator’s Y= editor.
0
Automatically determine the equation that best fits the data using the calculator’s
0
regression capabilities.
Other relationships can be explored beyond those represented by the plot options in
RANGER
as statistical plots. From the
Plot1
. For instance, simultaneous plots of Distance-Time and Velocity-Time can be viewed
as L1 versus L2 and
MAIN MENU
as L1 versus L3. (You may also need to adjust the Window.)
Plot2
in the
RANGER
program, choose
, and then set
QUIT
Data and plots can be sent to a computer using TI-Graph Link. This is especially useful when
students generate more involved reports of their activity findings.
Using CBR without the RANGER program
You can use
For information on using
0
For information on obtaining programs and activities, see page 36.
0
For information on programming commands to write your own programs, see pages
Function explored: linear.
MATCH introduces the real-world concepts of distance
and time—or more precisely, the concept of distance
versus time. As students attempt to duplicate graphs
by walking while seeing their motion plotted, the
concept of position can be explored.
In Explorations, students are asked to convert their
rate of walking in meters per second to kilometers per
hours.
Once they have mastered the Distance-Time match,
challenge your students to a Velocity-Time match.
A TI ViewScreené allows other students to watch—
and provides much of the fun of this activity.
Hints
Students really enjoy this activity. Plan adequate time
because everybody will want to try it!
This activity works best when the student who is
walking (and the entire class) can view his or her
motion projected on a wall or screen using the TI
ViewScreen.
Typical answers
1. time (from start of sample); seconds; 1 second;
distance (from the CBR to the object); meters;
1 meter
2. the y-intercept represents the starting distance
3. varies by student
4. backward (increase the distance between the CBR
and the object)
5. forward (decrease the distance between the CBR
and the object)
6. stand still; zero slope requires no change in y
(distance)
7. varies by graph; @yà3.3
8. varies by graph; @yà1
9. the segment with the greatest slope (positive or
negative)
10. this is a trick question—the flat segment, because
you don’t move at all!
11. walking speed; when to change direction and/or
speed
12. speed (or velocity)
13. varies by graph (example: 1.5 meters in 3 seconds)
14. varies by graph; example: 0.5 metersà1 second
Guide the students to walk in-line with the CBR; they
sometimes try to walk sideways (perpendicular to the
line to the CBR) or even to jump up!
Instructions suggest that the activity be done in
meters, which matches the questions on the student
activity sheet.
See pages 6–12 for hints on effective data collection.
Typical plots
example: (0.5 meters à 1 second) Q (60 seconds à
1 minute) = 30 meters à minute
example: (30 meters à 1 minute) Q (60 minutes à 1
hour) = 1800 meters à hour
example: (1800 meters à 1 hour) Q (1 kilometer à
1000 meter) = .18 kilometers à hour.
Have students compare this last number to the
velocity of a vehicle, say 96 kilometers à hour
(60 miles per hour).
15. varies by graph; sum of the @y for each line
segment.