Distributive Doctors

A complex mathematical concept when described, but completely understandable with hands-on, immersive learning. The distributive property of multiplication!

Definition: the property that terms in an expression may be expanded in a particular way to form an equivalent expression (www.dictionary.com)

To third graders (and most adults), that definition is mind boggling. Enter Dr. ________________ (insert your name here). Each year I arrange to have this hour-long activity take place after a classroom break. Often I set it up when the kids are in a special (art, music, PE), because I need about 30 minutes to change the classroom into a hospital operating room and I want it all to be a surprise. The day before I will gather the needed materials (trays, counters, jumbo craft sticks, small paper plates, Q-tips, red tempera paint, tissues, dry erase makers, laminated practice sheets, and copied worksheets . . . plus my white lab coat, stethoscope, Dr. name tag, and “Operating Room X” sign for the classroom door). When the kids are gone, I rearrange their desks into three large OR table groups. The trays are set with the needed supplies for elbow partners (resident buddies) to share as they work together in their training. I pick the class up in my costume, so they are already reeling with curiosity. When we reach the classroom entrance, I stand next to the operating room sign and greet each student with “Good morning, Dr. Kirk” or “Welcome to the OR, Dr. Smith.” I use a prepared SMART Notebook file with “case studies” of patients that have a diagnosis (7 X 8). I ask for their advice on which operation to perform to “cure” the patient. Using the jumbo craft stick as a scalpel, I model how to cut apart the large array into two smaller, more manageable arrays (2 X 8 and 5 X 8) on our document camera. Once we do 3-4 examples on the board, they get the idea and are ready to try it with their partners. Now they can use some of the materials on their trays. I continue using the SMART Notebook file with patient profiles. The teams set up the scenario using the counters and discuss how to operate. The laminated sheet has the template __ X __ = (__ X __) + ( __ X __ ) so they can practice writing the larger array and showing how it can be broken up into two smaller arrays. After a few rounds of guided practice, they graduate to independent work using red tempera paint and Q-tips on the worksheet. This time I provide the “patient diagnosis” (full equations such as 6 X 7), which they dot with paint. Then they must decide where to “cut” (draw a line to separate it into two smaller arrays). Finally, students write the math equations to document their understanding of the property. Any “residents” that finish early and have “cured” all of their patients, are given the challenge of assisting any classmates who need more coaching.

This concept can be quite boring and confusing on its own. But turning the lesson into an experience really helped my students learn it and love it!

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