Pumpkin Seed Multiplication

This week I introduced the class to multiplication, and I was able to revive one of my favorite math lessons.  Mrs. McMurphy's math class joined us, and we used the science lab to conduct this two day experiment.  First, we reviewed some facts about pumpkins, how they grow, different varieties, etc. I read "How Many Seeds in a Pumpkin" by Margret McNamara and Brian Karas. This is an excellent little book about a class that is learning about multiplication.







The class was then divided into two teams.  One team had a small white pumpkin, and the other team had a large orange pumpkin.  We made predictions about how heavy the pumpkins were, how many stripes they had, the circumference, and of course, how many seeds they have.

We checked our checked our predictions about the weight, circumference (both metric and standard), etc.  I was vey impressed at how close many of the students' predictions were!





We then cut open the pumpkins, took out the seeds, cleaned and toasted them.

Today we brainstormed ideas about the best ways to count the seeds.  I was relieved when the class decided on their own that the best way to count the seeds was to divide them into groups of 2s, 5s, or 10s.  With that, the class was divided into two "clubs," the Twos Club, and the Fives Club.  The Twos Club made arrays of seeds in groups of, and the Fives Clubs made arrays of seeds in groups of 5.

After all the seeds we sorted we skip counted all of the seeds.  

We then made repeated addition problems to represent our arrays.

Finally, we turned out repeated addition problems into more "efficient" multiplication problems and voila! we checked our predictions, worked in collaborative groups, learned problem solving strategies, multiplication has been introduced & made concrete, connected to prior knowledge and understanding, related to real world examples, and hopefully fun! 

A special thank you to Tanya Hand and Lori Aycock for donating the awesome pumpkins!