Transcript Lesson 5 PPT
Name:________________________________________________________________________________Date:_____/_____/__________
QUIZ DAY!
Fill-in-the-Blanks: 1) When adding SAME signs, we _____ and keep the sign.
2) When adding DIFFERENT signs, we ___________ and keep the sign of the larger _______________________ .
3) All subtraction problems can be re-written as ___________ problems because subtracting is also adding the _____________. Change the following subtraction problems into addition problems (KCC): 4) 5 – 11 5) 2 – (-4) 6) -5 – 9 ONLY use KCC for SUBTRACTION!!
Evaluate (mix of both addition and subtraction problems): 7) 8 – 20 = _____ 8) -25 + 19= ____ 9) -5 – (-9) =_____ 10) -50 + 60 = ____ 11) -2 – 11 = ____ 12) 20 – ( -8) = ___
Today’s Lesson:
What: Multiplying and dividing integers Why: To establish the rules for multiplying and dividing integers.
Models for multiplication and division:
Three groups of negative 3 is -9!
Two groups of negative 5 is -10!
Model the following problem on the below number line: 4(-2) = -8
Algebra tile (integer chip) models:
- -6 ÷ What other problem is this a model of ???
Draw integer chips (use space below) in order to model the following problem: -8 ÷ 4 = -2 What multiplication problem is this? ___ x ___ = ___
Rules for multiplying And dividing integers: SAME SIGNS DIFFERENT SIGNS ____________ _ ANSWER
3 ● 4 = 12 -3 ● -4 = 12 6 ÷ -6 ÷ 3 = 2 -3 = 2
____________
NEGATIVE
_ ANSWER
-3
●
3
●
4 = -12 -4 = -12 -6 ÷ 6 ÷ 3 = -2 -3 = -2 Evaluate: 1) -3(6) = 2) -4(-4) = 3)
−24 8
= Don’t confuse these rules with the addition rules!
4) −100
=
−10
-18 16 -3 10
Multiplication/ division memory “tricks”:
1) Tic-Tac-Toe . . .
Fill in your letters . . .
N N N N N N
P= positive N= negative Make a Tic-Tac-Toe Board with “P’s” in the diagonal and “N’s” in all the other spaces. Read board in any direction— up, down, left, right, diagonal– from the outside in, and it will give you the right answer.
2)
Smiley Face Method:
We like to sleep!
We don’t like to be hit in the eye!
+ + + + -
3) Triangle Method . . .
Make a triangle and label the three corners with “P” at top and “N’s” on bottom corners. Start at any corner, and “read” the triangle in any direction . . . Use either the rules OR a memory trick to evaluate the below : 1) -5(-4) = 2) 2(-9) = 3)
36 −6
= 4)
−50
=
−2
20 -18 -6 25
Video break . . .
Let’s do this !!
Evaluate the following examples: 1.
8(-6) =
2.
-12(-3) =
3.
-11 ∙ 7 =
-48
4.
24 ÷ - 4 =
36
5.
-28 / -7 =
-77
6.
150 / -5 =
-6 4 -30
IXL HOmework
C.6
C.7
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• • •
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END OF LESSON
The next slides are student copies of the notes for this lesson. These notes were handed out in class and filled-in as the lesson progressed.
NAME: Math-7 NOTES What: Multiplying and dividing integers DATE: ______/_______/_______ Why: To establish the rules for multiplying and dividing integers. Models for multiplication and division:
Three groups of negative 3 is -9!
3(-3) = ____ Two groups of negative 5 is -10!
(__)(__) = ___ Model the following problem on the below number line: 4(-2) = -8
Algebra tile (integer chip) models:
What other problem is this a model of ???
2 x _____ = -6 ___
÷
_____ = _____ Draw integer chips (use space below) in order to model the following problem: -8 ÷ 4 = -2 What multiplication problem is this? ___ x ___ = ___
Rules for multiplying And dividing integers: SAME SIGNS ________ ANSWER
3 ● -3 ● 4 = 12 -4 = 12 Evaluate: 1) -3(6) = 6 ÷ -6 ÷ 3 = 2 -3 = 2 2) -4(-4) =
DIFFERENT SIGNS _________ ANSWER -3 ● 3 ● 4 = -12 -4 = -12
-6 ÷ 6 ÷ 3 = -2 -3 = -2 3)
−24 8
=
4) −100
=
−10
1)
Multiplication/ division memory “tricks”:
Make a Tic-Tac-Toe Board with “P’s” in the diagonal and “N’s” in all the other spaces. Read board in any direction— up, down, left, right, diagonal– from the outside in, and it will give you the right answer.
P= positive N= negative We like to sleep!
2) Smiley Face Method: Smile = __________ answer Frown= __________ answer We don’t like to be hit in the eye!
3) Make a triangle and label the three corners with “P” at top and “N’s” on bottom corners. Start at any corner, and “read” the triangle in any direction . . .
Use either the rules OR a memory trick to evaluate the below : 1) -5(-4) = 2) 2(-9) = 3)
36 −6
=
4) −50 −2
= VIDEO BREAK . . .
Let’s do this !!
Evaluate the following examples (show work when needed): 1. 8(-6) = 2. -12(-3) = 3. -11 ∙ 7 = 4. 24
÷
- 4 = 5.
−28 −7
= 6.
150 −5
= IXL: C.6 & C.7
NAME:________________________________________________________________________________DATE: _____/_____/__________ Math-7 Individual practice
“Multiplying/ Dividing Integers” Model the following multiplication problems on the given number lines:
17) 3(-2) = 18) 2(-4) =
Model the following multiplication/division problems with algebra tiles (integer chips):
19) 3(-4) = ___ 20) -8 ÷ 4 ___