Texas Instruments TI-15 - Related Procedures; Constant Operations

© 2000 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
TI-15: A Guide for Teachers
20
Related Procedures
Grades 2 - 6
Overview
Students will use the two constant operations (
›
and
œ
) to compare the results of different
mathematical procedures and determine how they
are related.
Math Concepts
• whole numbers
• addition,
subtraction,
multiplication,
division
• fractions
(Grades 5-6)
• decimals
(Grades 5-6)
Materials
• TI-15
• pencil
• student
activity
(page 23)
Introduction
1. Have students program
›
with +2 and
œ
with -2.
2. Have students enter
8
on their calculators, press
›
, and read the output (
1 10
, which means
adding 2 once to 8 gives 10).
3. Have students press
œ
to apply the second
constant operation to the output of the first
constant operation, and then read the output
(
1 8
, which means subtracting 2 once from 10
gives 8).
4. Have students continue this process with various
numbers as their first input. Discuss their results.
(Pressing
›
and then
œ
always gets you back
to the first input number, which means
›
and
œ
are inverse procedures.)
5. Challenge students to find more pairs of
procedures for
›
and
œ
that will follow the
same pattern and record their investigations
using the
Related Procedures
student activity
page.
³
To use
›
and
œ
:
1. Press
›
(or
œ
).
2. Enter the operation
and the number (for
example,
T
2).
3. Press
›
(or
œ
).
4. Enter the number to
which you want to
apply the constant
operation.
5. Press
›
(or
œ
).
The display will have
a
1
on the left and the
result on the right. If
you press
›
(or
œ
)
again, the calculator
will apply the constant
operation to the
previous output and
display a
2
at the left,
indicating the
constant operation
has been applied
twice to the original
input.