Presentations text content in Multiplying Integers with Tiles
Slide1
Multiplying Integers with Tiles
Student Expectation:
7
th
Grade:
7.1.2C
Use
models, such as concrete objects, pictorial models, and number lines, to add, subtract, multiply, and divide integers and connect the actions to algorithms.
Slide2MULTIPLICATION
Red and yellow tiles can be used to model multiplication. Remember that multiplication can be described as repeated addition.So 2 x 3 = ?
The University of Texas at Dallas
2 groups of 3 tiles = 6 tiles
Slide3MULTIPLICATION
2 x -3 means 2 groups of -3
The University of Texas at Dallas
2
x
-
3
=
-
6
Slide4MULTIPLICATION
Since 2 x 3 = 6 and 3 x 2 = 6, does it make sense that -3 x 2 = -6 ? -3 x 2 = -6 is true. +2 x -3 = -6 and -3 x +2 = -6 belong to a fact family:
The University of Texas at Dallas
+
2 x
-
3 =
-
6
-
3 x
+
2 =
-
6
-
6
÷
+
2 =
-
3
-
6
÷
-
3 =
+
2
Slide5MULTIPLICATION
Use your tiles to model each multiplication problem.+2 x +4 = ?
The University of Texas at Dallas
ANSWER
2 groups of
+
4
+
2 x
+
4 =
+
8
Slide6MULTIPLICATION
+3 x -3 = ?
The University of Texas at Dallas
ANSWER
3 groups of
-
3
+
3 x
-
3 =
-
9
Slide7MULTIPLICATION
-2 x +4 = ?
The University of Texas at Dallas
ANSWER
4 groups of
-
2
-
2 x +4 = -8
Use the fact family for
-
2 x
+
4 = ?
We can’t show
-
2 groups of
+
4
+
4 x
-
2 = ?
we can show 4 groups of
-
2
Slide8MULTIPLICATION
+1, -1 are opposites the products are oppositeSince +2 and -2 are opposites of each other, +2 x -3 and -2 x -3 have opposite products.
The University of Texas at Dallas
+
1 x
+
3 =
+
3
-
1 x
+
3 =
-
3
Slide9MULTIPLICATION
To model -2 x -3 use 2 groups of the opposite of -3
The University of Texas at Dallas
-
2 x
-
3 =
+
6
Slide10MULTIPLICATION
Use tiles to illustrate -3 x -4 =?
The University of Texas at Dallas
ANSWER
3 groups of
+
4 (the opposite of
-
4)
-
3 x
-
4 =
+
12
Multiplying Integers with Tiles
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