Decomposing 2 & 3

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SWBAT show the different ways to "make" 2 and 3 with 2-colored counterl

Big Idea

Using simple 2-color counters, we will develop a process to decompose 2 & 3.

Attention Grabber/Introduction

5 minutes

“Girls and boys, is this 2?” I ask, showing 2 red counters on the big screen. 

“Well, yeah, Ms. Novelli,” students respond.

“Hmm… is  this 2?” I ask, showing 2 yellow counters on the big screen.

“Yes!’  they exclaim.

“But 2 red… 2 yellow… are they the same?” I ask.

“No!” students respond.

“But you told me they’re both 2!”  I’m confused, I say, hoping my acting skills are paying off.

“Yellow can be 2 and red can be 2,” a student says matter-of-factly.

“But they’re not the same… and they are the same?  How can different things be 2?” I press on.

“Well, as long as you have 2 of them, you can have 2 different things,” a student says.

“So there are different ways to make 2,” I say.  “Let’s check them out!’

Guided Practice

20 minutes

We begin with 2 red counters, and we color them in to record the combination on our recording page.  We even total 2 red and 0 yellow.  (The concept of 0 gets tricky sometimes… they always want to say there’s something!)

Next, we systematically flip over 1 red from the right side and we again color and write the numbers.

I have the students tell me to make the last red yellow, so that it’s all yellow, and we record our possibility.

Three is on the back, and for a moment, I totally forget my head.  We do the first group of 3 together—just like we did for 2.

The students seem to be doing really well, and they ask to practice all by themselves, and I make a huge mistake and say, ‘Sure.”

Some kids start randomly flipping counters, and I see we have a mess.  I try to swoop I and help a confused friend, but ultimately, I’m waiting for a chance to re-teach this!


5 minutes

Students show their different combinations to make 2 and 3.  There are a lot of different combinations showing 2 red and 1 yellow or 2 yellows and 1 red. Hmm.  We don’t quite have this concept “down,” I realize.