Thursday, October 3, 2013

Multiplication, Mice, and Math practices

I can hardly believe October is here!  With cooler weather comes one of the concepts that students are most excited to learn about in 3rd grade...multiplication!  I've written before about how important the idea of multiplication is in 3rd grade, and how the progression of concepts eventually leads to the concept of the Distributive Property, but did you know that multiplicative concepts encompass an entire critical area in 3rd grade Common Core?!?!  Let's just think about that for a second and 'word-nerd' it-- According to
1. containing or making severe or negative judgments
2. containing careful or analytical evaluations: a critical dissertation
3. of or involving a critic or criticism
4. of or forming a crisis; crucial; decisive: a critical operation
5. urgently needed: critical medical supplies
6. informal  so seriously injured or ill as to be in danger of dying
7. physics  of, denoting, or concerned with a state in which the properties of a system undergo an abrupt change: a critical temperature
8. go critical  (of a nuclear power station or reactor) to reach a state in which a nuclear-fission chain reaction becomes self-sustaining
Basically, with the help of multiplication, our 3rd graders will reach a state of nuclear-fission!!  But in all seriousness, I think the fifth definition sums it up best, multiplicative concepts in 3rd grade are "urgently needed" so that our students have a foundation so strong enough to support and deepen their understanding of later concepts and grades.

So, obviously, multiplication is important, but how do we, as teachers, build that strong foundation?  For us, we start by thinking about the math ideas necessary to truly understand the concept of multiplication.  Together with my amazing third grade team, we mapped out what we believe to be a logical progression of ideas that would support the bigger idea of multiplication in 3rd grade.  Here is what we came up with: repeated addition, skip counting, equal groups, arrays, area models (area as additive, then multiplicative), and eventually, the concrete proof of the Distributive Property.  In reality, these ideas will be the primary focus of our math instruction, and will take us until about mid-November until we move on to other (related) concepts.

We are currently in our third week of building multiplicative concepts in 3rd grade, and I can definitely say that my students are using a very wide variety of strategies to solve our multiplication math tasks.  Today, we completed a "Mouse Problem" in which students were asked to select a number of mice to "buy" from the pet store.  Each year, their mouse population increases in size (2nd year, population doubles, 3rd year it triples, and so on), and students were asked to figure out how many mice they would have by the 5th year.

Skip Counting in parts
Multiplication with repeated addition

And some of our progress with Math Practice Standards...

This last pic is my fav because it is SO 3rd grade.  This student had a very interesting patterning strategy to find their products, and was extremely ambitious in the original number of mice they started with (501), but check out the "math" vocabulary!  I LOVE "sixdupal" and the others that follow it, and I can definitely appreciate an attempt at attending to precision in our mathematics vocabulary.

Now that October is here, what are you working on in your classroom?


  1. Wow it's crazy to see how far ahead 3rd graders are! As a first grade teacher, we are currently working on number bonds and different ways to get a certain number. =)

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    Just Wild About Teaching

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