Fall baking in our house requires canned pumpkin. We were out so I asked for Tabitha’s help at the grocery store, where the pumpkin in on the bottom shelf.

Me:Put four of those bright orange cans of pumpkin in our cart, please.

Tabitha(6 years old): I don’t know if I can carry four.

Me:Do two, then two more.

T: [With two cans of pumpkin in her hands] I know, because two plus two is four.

Me:Right. You could do three and one, I suppose.

T: OK. Give me one back.

She takes it, picks up two more from the shelf and brings the three cans over to me.

T: I did two and three.

Me:So we have five cans?

T: No! You gave me one back, remember?

Me:So two plus three minus one is four?

T: Yeah.

# So what do we learn?

Decomposing numbers is fun.

We tend to think of 2+2 as something to do, and that the answer is 4. But in this case 4 is the thing to do, and 2+2 is one of several possible answers. When we think about different ways to make 4, we are decomposing 4.

Tabitha can keep track of the moves in our complicated decomposition at the end (*You gave me one back, remember?*) but she does not have practice with the math notation that captures all of these moves (*Two plus three minus one is four*). That is one of my roles in the conversation.

# Starting the conversation

Tabitha gave me the ideal beginning to this conversation—she pointed out that there were too many cans for her to carry. It shouldn’t be difficult to put your own child in such a situation. The grocery store sells lots of things that children can carry a few of, but not a lot of: apples, oranges, cans of soup, etc. Picking up toys at the end of a play session at home or school, or books at the library—all of these are opportunities for you to name the number involved, then suggest a way to decompose it.

Hi, Christopher,

I have a question, if I may; Syd, our 1st grader, is having difficulty with the ‘ones and tens’ concept. She’s taking 30 minute intervention sessions 3 days per week at school to help her along. (I was unaware of this. Her teacher just sent me an email today informing my husband and I.)

We’ve been using beans, candy corn, Leggos in trying to help her along in grasping the concept. Are there any other examples you could give us in helping Syd? We’d appreciate that greatly.

Eva

Reblogueó esto en ciencia y conciencia universal + cosmica cd 2014.

I think you are doing more than decomposing numbers – you are building equations and even algebraic thinking. Neat!

Just barely started reading this blog and have to say I really enjoy it, way to make a potentially difficult topic for kids and parents enjoyable