Math = Love: Teaching the Distributive Property

## Friday, September 7, 2012

### Teaching the Distributive Property

After having to reteach my Algebra 2 students the distributive property, I wanted to make sure my Algebra 1 students had a strong understanding of the distributive property.

Looking online for ideas, I found the idea of teaching the distributive property using combo meals.

 Distributive Property Using the Concept of a Combo Meal
I printed off pictures of various foods.  I cut them out and laminated them.  Then, I glued magnets to the back.  If you're wondering why I included apples and bananas with my fast food, well I can tell you it's not because I'm crazy.  Instead, I wanted to use these again whenever I teach combining like terms using the banana rule for combining like terms.

I started off by asking students what the cheapest way to get a burger, fries, and a drink were at a fast food restaurant.  I hoped they would suggest a combo meal.  While each class eventually did suggest that, many students instantly replied "The Dollar Menu."

Using my magnets, I created 2 combo meals.  We discussed how to write each combo meal as an algebraic expression.  Of course, the students had to criticize my choices of foods for the combo meals.  Apparently fritos are gross.  And, I've learned that nobody in their right mind would drink diet dr. pepper.

 Distributive Property Using the Concept of a Combo Meal

I think my students thought that by making magnets of a certain food I was somehow endorsing it.  Honestly, I don't drink pop at all.  I only picked Diet Dr. Pepper because it wouldn't use as much printer ink as other brands would.  And, on top of that, I'm a vegetarian.  So, I don't eat hamburgers or hot dogs.

When we talked about how many hamburgers we would get if you ordered 5 combo meals, the students knew the answer straight away.

When we moved onto problems that didn't involve food, things didn't go as well as I thought they should have.  Students could see why we would multiply everything in the combo meal by the number outside of the parentheses.  But, one student wanted to argue that since there was only 1 number outside of the parentheses, we could only multiply one of the terms inside of the parentheses by that number.

I had students create a foldable with the four different variations of the distributive property.  I left my interactive notebook at school, so I don't have a picture of it at the moment.  It was nothing spectacular, but it was better than just writing down the four rules.
 Student example of left side page.  Students created their own combo meal to demonstrate the distributive property.  This student didn't draw all of their arrows, but their illustration was much more photo worthy.

Finally, I had students create their own combo meal on the left side of our INB.  Students had to draw a combo meal of their own.  Then, they had to write it as an algebraic expression.  Finally, they had to choose how many of that combo meal they wanted and use the distributive property.

1. I love this idea! Thank you for posting! I can't wait to try this in my Algebra I class.

2. This is excellent! Can't wait to do this with my kids! Thank you for sharing! -6th Grade Math Teacher, Bronx, NY

3. I LOVE this idea. I'm tutoring a student over the summer, and I wanted to give her a fun way to introduce algebraic properties. I really wanted her to feel comfortable about properties to give her the confidence in her future math classes. I will definitely use this. Thank you so much!

1. Glad I could inspire you!

4. Thank you for sharing! I'm an English teacher in High School and have recently been assigned to teaching 7th-8th grade combo class this fall. Having never taught math, I've looked online for ideas. I can't wait to use your idea! phew..thanks!

5. this was amazing, and very kid and visual friendly. Thanks!

6. this is a great idea, and using a smart board makes it super easy!

1. I haven't tried it on the SMART Board yet. Great idea!

2. Hi Sarah,
I made a SmartBoard lesson to go along with your combo meal. I'm going to use it with my Pre-Algebra students this week. Thanks for the great idea.

Jan at equationfreak.blogspot.com

7. Nice idea. I would like to put forward the idea that using the pronumeral in place of an object is a little misleading. The "letter as object" model does not really represent the realm of real numbers and how they behave. Would you like fries squared with that?
A great paper on this misconception amongst teachers can be found here: http://www.merga.net.au/documents/Chick_RP09.pdf

1. Thanks for the link. I will definitely read more about this during this summer. I actually haven't explicitly taught the distributive property since 2012 when I wrote this blog post. This should give me some food for thought.

2. This could easily represent real numbers and how they behave by simply using the same model but using the price of each item, instead of the item itself. So not "fries squared", 2 dollars squared.

8. What exactly do you mean by the four variations of the distributive property?
I really like the idea of using the combo meal as an intro to the distributive property, though! I think that is an awesome real-world type example!!

1. It referred to some notes I had my students take. I don't teach it like this anymore, though.

9. I am starting this tomorrow with my year 10 students (this is students who are 13-15 years old) Probably the same as a freshman year level. They are quite low level of understanding too. So i a going to try the combo idea. They love food. Thank you for your ideas. You are rocking my teaching

10. Yay! This is perfect! First year middle school math teacher here -- I've been using food analogies for teaching expressions the past couple weeks -- started with ordering at fast food places - how we don't say we need a burger and another burger (b+b), we just say we need 2 burgers (2b) -- so this is going to fit perfectly! Just in time to teach it tomorrow! Haha! Thanks!

11. You are very creative in your activities. Thanks so much for sharing.