Thursday, November 17, 2011

[And this is why I love First Grade]

Yesterday's activity went well.
It was a really tough process and involved a LOT of think time.
A LOT of questioning.
And a LOT of proving and disproving our conjectured (is that even a word?!) rule when zero is an addend in a 2 addend equation.
Then, to take that even further. . .what is the conjecture when zero is the subtrahend in a subtraction equation?!
Ha!  Don't tell me first graders can't do stuff like this.  :)

We used Smarties and the part-part-whole workmat.
We did some mental math.
We even used calculators!!!
Gasp.  Yes.  Calculators in First Grade.
You know what?!  They totally rocked it.

And, even better, Mr. CB informed me that their conjecture WAS true when it stated, "When you add zero to any number, the sum is the first addend."  I questioned him, asking him to prove his thinking while I wrote 0+5 on the board.  His answer? 
"That's the commutative property of addition, so you'll have the same sum, but you're not adding zero.  You're adding five."
So. . .we reworded the conjecture into the proof that says, "In a 2 addend equation, when zero is one of the addends, the sum is the same number as the other addend."

They get it.
They can explain it.
They can make the connection between adding and subtracting zero.
They can prove what they know.
They can speak mathematically.  And make sense!  ;)

And this, my friends, is just one of the reasons why I love First Grade!

Today we're on to subtracting 1.
Our lesson guide uses the terminology "1 less than ___ is ____" and then asks the students to write the equation.
It's tough.
We're going to do a series of problems using that wording and the 2nd step of writing the equation while working with a number line and a little treat.
We'll be fine.

Tomorrow it's on to subtracting ALL.

Happy Thursday!


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