Download Decompose Math Facts

Decompose Math Facts
Learning target: develop facility with math facts by decomposing numbers
Supplies: small white boards (pair of dice, optional)
Instructions for facilitator:
1.
2.
Roll die and use results to multiply.
Introduce vocabulary: multiplier, multiplicand and product. (For example, in 8x4, 8 is the multiplier
and 4 is the multiplicand.)
3.
4.
Now ask students to come up with two numbers yield the product when multiplied.
Students will notice there were only a fixed number of ways to do this. However, some will come up
with the number 1. This is the identity property of multiplication.
5.
6.
7.
Roll the die again and develop another set of possible factors.
Create the math sentence to show the equation. Repeat steps 1-6.
Create a table showing the fact families developed so far. Notice any patterns, such as for the 9
family the last digit of the answer decreases by one every step while the second digit increases by
one, from 9, to 18, 27, 36 and so forth.
Extensions:
1.
If the product is not known right away, find several other ways to construct it by decomposing the
multiplier and multiplicand into “friendlier” options.
2.
3.
How many ways can students solve a problem such as 25 x 9?
What about 25 x 29? Can decomposing numbers help with large problems? How does knowledge of
base 10 help find the product?
Submitted by: Tammy Deets