© 2000 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
TI-15: A Guide for Teachers
34
What’s the Problem?
Grades 2 - 5
Overview
Students will connect number sentences to problem
situations and use addition, subtraction,
multiplication, and division to solve the problems.
Math Concepts
• addition,
subtraction
• multiplication,
division (Grades
3 - 5)
• number sentences
(equations)
• inequalities
(Grades 3 - 5)
Materials
• TI-15
• counters
• pencil
• student
activity
(page 37)
Introduction
1. On a sentence strip or on the overhead, display a
number sentence such as “8 + 2 = ?” Have
students brainstorm situations and related
questions that this number sentence could be
representing. For example, “If I bought eight
postcards on my vacation and I had two
postcards already at home, how many postcards
do I have now?”
2. If necessary, have students act out the situation
with counters and determine that the value of “?”
is 10.
3. Demonstrate how to display this equation on the
calculator, and how to tell the calculator what
the value of ? is.
4. Now display an equation such as ? - 10 = 5. Have
students brainstorm situations and related
questions that this number sentence could be
representing. For example, “I had some money in
my pocket, and I spent 10 cents of it. I only have
5 cents left. How much money did I have in my
pocket to begin with?” Have students practice
the keystrokes necessary to display this equation
and test the value they determine for “?”.
5. Over a period of time, continue to introduce
students to different types of number sentences
to explore. For example, ? - 8 < 5 (which has 13
whole number solutions) and ? x ? = 24 (which
has 8 solutions of whole number factor pairs)
and ? x 4 = 2 (which has no whole number
solution).
³
To display this equation
on the calculator, put
the calculator in
Problem Solving mode
by pressing the
‹
key.
Then enter the equation
8 + 2 = ?
and press
®
. The calculator
display (
1 SOL
) tells
how many whole
number solutions there
are to the equation.
To test your solution to
the equation, enter the
value of
10
and press
®
. The calculator will
display
YES
.
³
If an incorrect value is
tested for
?
, the
calculator will display
NO
and provide a hint.
For example, if a
student tests 5 for the
equation
? - 10= 5
, the
calculator displays
NO
,
then shows
5 - 10 < 5
,
and then returns to the
original equation.
To Next Page
Loading...
Need help?
General
