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Packed with Math: 23 Digi-Block70
Fact Separations
Topic: Using known facts to derive a product.
In this activity students will:
Q Use blocks to model multiplication problems as arrays.Q
Separate arrays into partial products using known facts.
Q Calculate a product by finding the sum of its parts (i.e., 8 9
= (8 5) + (8 4)).
Setup: Student arrangement: Small groups (24)
Each group needs:
1 array mat
2 blocks-of-100 for each group
1 1015 strips of heavy paper
1 activity sheet for each student
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Digi-Block Packed with Math: 2371
Fact Separations
Introduction:r Pass out the array mats and blocks to each
group.
r Ask students to make a 6 7 array.
r Give students a paper strip. Have them separate the array into
two parts using the strip.
r Ask students to describe the two parts.Write several of these
combinations on the board:
6 7 = (6 5) + (6 2)
6 7 = (3 7) + (3 7)
6 7 = (6 4) + (6 3)
r As a class determine the total number of blocks
represented.
r Repeat with another example: 8 7.
r This time ask students to separate the array into facts that
they know, for example many
students already know 5, 2, and 10 facts. They can use these
facts to make the problem easier:For example, 8 7 = (8 5) + (8
2).
Activity:Hand out: one activity sheet per group.
Partners will:
r Build an array for 9 8.
r Separate the array into two parts.
r Calculate the product by adding together the two products.
Closure
r Have students describe how they determine the total number of
blocks. Make a list of
methods for calculating 9
8.
r Have students share other arrays they made.
Assessment:r Which facts do students know?
r Do students separate the array into products that may be found
through multiplication facts?
Extensions:r Have students make their own arrays on the second
activity sheet. You may fill in the blanks with
appropriate numbers or have students fill in the blanks
themselves.
17
6 columns of 7 6 columns of 7 6 rows of 7
6 x 2
3 x 7 3 x 7 6 x 4 6 x 3
6 x 5
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Packed with Math: 23 This page may be copied for classroom use.
Digi-Block
72
Name ________________________________________________
Make this array with blocks. Separate the array into two
parts.Draw what you did. Write the two parts and find the
total.
Fact Separations17
0 1 2 3 4 5 6 7 8 9
0
1
2
3
4
5
6
7
8
9
10
11
10
12
9 x =8 (___ x___ ) + (___ x___ )
Make more arrays with blocks and separate them into two
parts.Draw the arrays on the back of the paper.
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Digi-Block This page may be copied for classroom use. Packed
with Math: 23
73
Fact Separations
Name ________________________________________________
Make an array with blocks. Separate the array into two
parts.Draw what you did. Write the two parts and find the
total.
17
Make more arrays with blocks and separate them into two
parts.Draw the arrays on the back of the paper.
0 1 2 3 4 5 6 7 8 9
0
1
2
3
4
5
6
7
8
9
10
11
10
12
x = (___ x___ ) + (___ x___ )
