Last week I told the children that the Hershey's President was interested in having students help him with figuring out how to package his chocolates. Instantly after mentioning the word "chocolate" the students were completely engaged.
I began by reading the Hershey's Milk Chocolate Multiplication Book and followed this up with a Marilyn Burns lesson that I finessed to meet the needs of Division 5.
Next, each student was given four 1 x 1 cm brown squares. They were to pretend that each square represented an individual chocolate. I asked the students to explore how many different ways they could package their chocolates. Since we have already learned about 2-D shapes, the students understood when I told them that they could only make regular shaped polygons, such as a square or rectangle.
Quickly the students were volunteering their answers...
It could be a 1 x 4 - which lead me to explaining that this was called an array. I always remind the students that when we are doing mathematics, we speak the language of mathematicians. We added the word "array" to our Math Word Wall.
Another student then offered that the chocolates could also be packaged as 2 x 2.
Then we had a real "ah-ha" moment when a student asked whether or not a 4 x 1 array would count as a third option, or was it the same as a 1 x 4.
Instead of answering this student, I asked the class if anyone had any thoughts. Someone suggested that since this shape was "congruent" (YES, that was the term used - I did a happy dance!) that it would not count as a third option.
Another student put his fist up in the hang-loose hand signal (which I have used with a clicking sound to teach the commutative principle) and told us that it was true for addition and multiplication. Then together the whole class did the hang-loose motion together. The commutative principle, simply put, states that any factors in a multiplication statement can be switched place, and the product (answer) will remain the same.
Following the class example, the students were put into cooperative groups and given 6, 12, 18, 24, and 36 squares of pretend chocolates and challenged to discover how many different ways they could be packaged. The students were very creative in explaining why they felt the 'President' should chose one array over another. We concluded the lesson eating mini-Hershey's chocolate 2-square bars!
At the suggestion of my class, I have sent an email to the Hershey's Company detailing this lesson and how much fun the students had. I think they are hoping for some free samples! ~ as am I.