Sunday, February 7, 2016

The Snowflake Method for Factoring

Needless to say, I am more than a few days late on this post. I meant to do this a couple of weeks ago, but last week was insane. I had basketball games on Monday, Tuesday, and Friday. I went to eat with my girlfriend and a friend that I hadn't seen in a while. I had school on Thursday, an Education Association meeting at the elementary school that lasted until near 6:00. I then had to grade tests for an hour and a half, which meant that it was 7:30. I went down to Subway (which is walking distance from my house) and grabbed a sandwich. I also didn't get a planning period on Thursday due to watching another class and a post-conference about my evaluation with my principal. Then I had to tutor a kid for most of my planning on Friday, which meant that I got lesson plans done about two hours ago.

Anyways, let's talk about the Snowflake method for multiplying trinomials. I first learned this method from a colleague in Greenville, Mississippi during my first year of teaching. I have used this method from then until now. I didn't use it last semester, but I feel like it's a trusty method for the most part. After not using it last semester, I decided it was time to dig it back out for students.

To do the snowflake method, here are the following steps.
  1. Label a, b, and c, which is standard for working with quadratics in the form ax^2+bx+c=0
  2. Draw your snowflake, which is an x with a horizontal line through the center. 
  3. Place the a terms on the sides above the center line. 
  4. Place a*c at the top. 
  5. Place b at the bottom (b for bottom).
  6. Find your two factors that multiply to get a*c and add to get b. 
    1. It's still guess and check, though. 
  7. Take the sides of your snowflake and write as binomials.
  8. Check using distributive property.
Here is a link to a video I made using ShowMe. Snowflake Method for Factoring. Check it out! 

Here are a few pics from our classroom. If you have any questions about the Snowflake Method, please feel free to contact me by filling out the contact me form on the side of the blog. I would love to discuss the method with you. 


  1. To me I think using a generic rectangle makes more sense, with the aid of a diamond problem. The snowflake confused me a little bit. I have you seen CPM's method? Check my blog the last 2 days.

    1. Thanks for stopping by! I have not seen CPM's method, but I will check out your blog. We don't have CPM here (or any textbook for that matter). The textbooks I have are from the old standards before CCSS, and I don't use them.

  2. So, I've never seen this method before. It's very similar to the slide, divide, bottoms up method I've used in the past, though. I thought it was funny that I saw your blog post on twitter about this method and another picture on twitter about the same method with a different name (asterisk method) on the same day for the first time ever.

    I will also second the generic rectangle method mentioned above. It's what I've transitioned to using over the past two years after using a zillion other methods with mixed success. I find that my students have a much more conceptual understanding of what is going on with factoring with the rectangles because we are able to use the rectangles to multiply polynomials, factor polynomials, and divide polynomials.

    1. Yes, I have taught using slide, divide, bottoms up method before. However, I couldn't get my kids to remember to bottoms up. I used this when I taught Algebra I in Mississippi, and I have used it in the past. Some of my former honors students who then took Pre-Cal loved snowflake. I think I might try the box method next year. That is pretty funny, actually! I am glad I am helping to contribute to the MTBoS!

      When I was in high school, we used trial and error, which finally clicked about the time I got to Pre-Cal. I use the box method to teach multiplying complex numbers and dividing polynomials. Actually, I have been doing box with dividing with my honors group. I introduced synthetic division, and most liked the box better. Success! I don't go into factoring as much since it's in the Algebra I standards, but I use it when we are solving quadratic equations by factoring.

      Also, are you going to TMC16? I am!


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