Wednesday, November 16, 2011

[The PROPERTY OF ZERO] Subtraction

First off, let me just say that I really, really like enVision math for First Grade.  I think it's a great mix of concrete/visual/abstract practice.  I know the kids enjoy the activities, and for the most part, I think it's a pretty sound program.
However. . .when it comes to subtraction.  Sigh.  For example.  This is our 2nd subtraction topic.  The first was taught after the first addition topic.  Then we taught another addition topic between the subtraction topics.  So. . .this is supposed to be review?
I don't know.  I just know that every year we struggle through both of the subtraction topics.

Today, for example is the first lesson in this topic.  And we're supposed to teach subtracting with 0, 1, and 2.  Seriously.
Yeah.  Not gonna happen!

I'm dividing that lesson into 3 components.  Subtracting with ZERO (today's lesson), subtracting ALL (tomorrow's lesson), and subtracting 1 (Friday's lesson).
Today we're going to talk about the property of zero within addition and subtraction.
We'll create a conjecture.  We'll show some proof.

Here's where we'll start. . .
And hopefully we'll have a deeper understanding of just exactly what happens when you subtract ZERO from a number.
(Anyone know why this is such a difficult concept in first grade?!).
Wish me luck!


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