Tuesday, May 18, 2010

Building Tens Family With Duplos

In first grade math, Rebekah had to add a column
of three numbers for the first time.

One of the tricks they taught
was to find  combinations of ten first.

We call these facts
The Tens Family.
Every member of this family has to = 10.

 First, I had Rebekah make stacks of Duplos,
from 1 to 10,  in two colors.

 While she was busy placing the stacks
neatly on my Quilting Mate,
I made a simple worksheet using Word.

Next, I had her fill in the worksheet,
combining the stacks of Duplos,
to find the answers.

From Left to Right
10 + 0 = 10
1 + 9 = 10
2 + 8 = 10
up to
10 + 0 = 10

I love how the Duplos clearly show the members
of the Tens Family,
and the beautiful patterning of numbers. 

They are bright, easy to use,
and make Math class feel like play time.
You could also use Legos,
if you don't have crawlers around,
who would feast on your manipulatives.

Next, I had her match up problems with the same addends.

(The numbers you add together are the addends.
The answer is the sum.)

This is the Commutative Property for Addition.
Remember that from Algebra?
a + b = b + a
1 + 9 = 9 + 1
2 + 8 = 8 + 2

For each math fact they memorize,
because of the Commutative Property,
they usually are learning two problems.

The exception?

You're right.
The doubles.
In this case, 5 + 5.

I use the term Commutative in first grade. 
Kids love big words.
If they can't remember the word, fine.
But, they can still understand the concept.

I tell my kids the smarter they are,
the less math they have to learn.
By using the Commutative property,
they only have to learn 6 problems
in the Tens Family, instead of 11.

Again, the Duplos clearly show the beautiful patterning
of the Commutative Property.
Scroll back up and admire the picture.

This is one of the reasons I love math!
You so easily see we have a God of order.

 We finished off the math lesson by easily tackling the math worksheet.
You can see where she swooped the numbers together,
to first make ten,
then add the third number.
(The other swoops were for doubles.)

I was so excited about this lesson,
especially since it is the end of the year,
and I am really, really, ready to quit.

 Beka later said,
"Math took a little longer than normal, Mom,
because you really got carried away."

To soften the blow, she added,
"But that's OK, Mom, because I like Math,
especially when you get to play with Duplos."