Piggy Bank Beginning Subtraction
Lesson 3 of 4
Objective: SWBAT use piggy bank mats and penny counters to practice subtraction.
As we come in after lunch, we have a read-aloud story, Benny’s Pennies. After a brief discussion about the story, including the fun of buying things, I show the fun, free piggy bank mat from Mrs. Ricca’s Kindergarten website. (Yes, I am definitely a fan of Mrs. Ricca! Thank you for sharing these adorable, useful math mats, Mrs. Ricca!)
I use 5 plastic pennies on a piggy bank mat projected on “the big screen,” and we make up a story about our helper of the day. We ask her how many of her 5 pennies she wants to spend and what she’s spending them on, and our helper models (MP.5) subtraction, actually sliding pennies out of the piggy bank, taking them away from the group of pennies in the piggy bank. We practice saying the subtraction sentence together, with all of us saying, “5 take away 3 is 2.”
At our tables, everyone gets a piggy bank mat and exactly 5 pennies. (I have the kiddos double-check that I’m passing out the correct amount, making sure that I’m precise. MP.6)
As a group, we begin with 5 pennies in the bank, a student is selected to roll the number cube, and then we slide that exact amount of pennies out of the piggy bank. We say the subtraction sentence as a group, but I follow it up by asking individual students to repeat the subtraction sentence. This allows me to check their learning, to keep learners who might want to “space out” actively engaged, and to, in a sense, heighten the level of attention, as no one knows who will be asked to tell us about the subtraction.
(I try to structure this carefully, asking 3 random kiddos per subtraction sentence, but I ask the student who might be confused more than other students to be the 3rd student in a group of 3, so that he or she just had 2 strong student examples, or models, of what he or she will be saying.)
We practice the process of taking pennies away many, many times—stressing the process of taking the pennies away from the piggy bank. To keep it fresh, fun, and relevant, we use students in our class and make up subtraction stories with their names and “buying popcorn for 2 cents” or “buying 3 pencils with 3 pennies,” which adds context and really hits the word problem standards. The subtraction stories are all about the students, and it is literally “hands on.” Again, we are actively building conceptual knowledge and experience with take away.
Each time we roll the cube and we practice “take away” with new amounts, I make sure to circulate the room, supporting all learners and keeping everyone engaged in this important work. I’m not sure if it’s the money or the fun of sliding, but even students who might be inclined to “tune out” are very interested in our math!
After collecting plastic pennies, I ask the students if they want to take their piggy bank mats home… thinking that they won’t want to take mats without counters home, but oh no! The students are SO excited to take their mats home!
I ask, in a silly voice, “But guys, if we don’t have counters to send home—I can’t give away the school’s plastic pennies, oh no!—what can you use for counters on your piggy bank mats?!?!”
“PENNIES!!!” the kids answer!
“Hmm… will you be able to find any of those? Will you be able to practice at home?” I continue, being so facetious and silly.
“YES!!!” students answer, with excitement and giggles.
We talk about having counters that they can find at home, and the kiddos reflect that it’s great to use stuff that’s easy to find around the house. “Then we can practice any time!” one student points out, while the group nods and smiles.