Factoring quadratic trinomials with cereal? Yes!

My students have always had a hard time factoring trinomials during our quadratics unit, probably because of the multiplication and backwards thinking. This year I started our unit with a whole lot of thinking and a whole lot of hands-on - with cereal!

Intro to Factoring
"What 2 numbers multiply to 12 and add to 13?" My students loved that one! It was a class favorite because it was so obvious...AFTER learning the answer:)

We started factoring with no trinomials in sight, just these types of number puzzles in this Let's Factor! PowerPoint.  Once the thinking was there, it made moving on to trinomials a whole lot easier and less intimidating.

After our number puzzles, I gave each group of students a bag of Cheerios and a factoring trinomials mat, and a trinomial to factor (also in the PowerPoint). We identified B and C together and students worked to find rectangles with areas of C.

In this trinomial, we needed to multiply to 12, so students counted out 12 pieces of cereal.The idea is that students will work their way though different arrays of cereal that make perfect rectangles and write down the side lengths.

As they worked their way through the different combinations, students wrote their pairs in the box and looked for a pair that add to B.

When I finally introduced the first actual trinomials, I heard a lot of, "This is light work!", which I have found to mean, "This is easy?". I loved it! Once the foundation was there, moving to negative numbers was a lot easier.

Improvements:
Some of my students had a hard time with the smaller size of the cereal we used. And they weren't as uniformly shaped as they would seem to be. In the future I will use larger cereal or square cheese crackers.

The factoring mat seen in this post can be found for free here.

Later when we get to graphing factored form quadratics, I give my students this factored form quadratics cheat sheet to reference during our unit.

I recently wrote a post about algebra tiles with photos and examples of how to use them to factor quadratic trinomials. There is a free printable set of tiles in the post.

I recently made this factoring trinomials math game called Voyage to the Treasure. In this game, students work together to beat the board and beat Math Monster to the treasure.

I wrote all about the fun quadratic activities we do during our unit in the blog post Fun with Quadratics. It includes a link to this factoring trinomials activity where students factor to find rectangle areas.

Unknown said...

Outstanding hands-on approach! I love this!

ScaffoldedMath said...

Thanks so much! I'm pretty geekily excited about factoring this year! :)

paula said...

I cannot stop reading all you are saying! I am so excited about all you are sharing.
Cannot thank you enough!!!

ScaffoldedMath said...

Paula, you are so kind! I hope you have a wonderful weekend:)

Cathie said...

Lesson planning for the 5 days I am allotted for factoring and this is definitely planned for day 1!

ScaffoldedMath said...

Five days! I WISH I could get through factoring in 5 days. It would never, ever be possible. Do you feel that is enough time?

When C is negative, I plan to explain that we will subtract the side lengths to get B. One of these days I'll actually write a post about the lesson! :)

Unknown said...

I'm going to try this tomorrow, super excited. Love the hands on approach! I also teach special ed Algebra 1. I couldn't find the powerpoint but that's ok :) Thank you for the idea

ScaffoldedMath said...

Ugh, why did I write "Powerpoint"? And I just now noticed how I linked it wrong! It should be fixed now. THANK YOU for letting me know! The Prezi was really helpful to my students. I hope they "get it" with the cereal!

Jokeburggirl said...

How do you extend this activity to examples with a coefficient of x squared greater than one?

ScaffoldedMath said...

Thank you for asking. For those I'd use algebra tiles. If you search "algebra tiles" here, a few posts will come up. There is a printable algebra tiles template linked in the factoring algebra tiles post if you don't have any.

Unknown said...

The Prezi link does have trinomials. Is this the wrong Prezi? I'm curious what the number puzzles look like.

ScaffoldedMath said...

Thank you for letting me know. I updated the link so it should go right to it now.

Unknown said...

That link still brings me to a Prezi with trinomials. The first slide is x^2+8x+7. Is this what it is supposed to be? I also don't see any sort of number puzzle, it is just trinomials and factored binomials.

ScaffoldedMath said...

(facepalm) I don't know why I had linked that Prezi. We did use that one, only later. I linked the PowerPoint we used with the number puzzles. Please send me an email if you'd like it.