Subtraction Number Stories- Day 2

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Students will be able to create their own number stories and represent them using one of the methods we have learned in this unit.

Big Idea

After reading If You Were a Minus Sign, students create their own number stories, by representing subtraction using pictures and possibly equations.

Problem of the Day

5 minutes

I start each math lesson with a Problem of the Day.  I use the procedures outlined here on Problem of the Day Procedures.

Today's Problem of the Day:

Jenny has 10 pieces of cake.  She gave 7 of them to her friends.  How much cake does Jenny have left?

I set this problem up with some structures to help the students organize their thinking.  I gave a blank number sentence frames to help the students to write their answer as an equation.  On the Notebook file, there is also a picture of a piece of cake set to Infinite Cloner.  This way the student can use it represent the problem.  If you do not have a SMART Board, you can use the PDF and manipulatives, pictures, or students' drawings.

Since we do this whole group, I have one students come up and work on this problem.  I remind the student to check their work when they are finished and have the class tell if they agree or disagree by showing a thumbs up or thumbs down.  Students also have the opportunity to share why they agree or disagree.

Presentation of Lesson

25 minutes

I start this lesson reminding students that we have been working on our "If You Were A Minus Sign" book.  I remind students that a minus sign is the symbol that we put between two numbers in an equation to show that we are subtracting.  By this point, we have been working with subtraction for a few weeks, so most students are comfortable with the name and purpose of a minus sign.


We have been working with writing subtraction number sentences which are also called equations.  Today we are going to continue to work on our books.  Let's start with a group number story.

I have students give me an idea for a number story.  I illustrate it on the same paper that they will be using and project it on the SMART board.  I have the students help me write the equation to go with it.  Here is our example from today.  I also model how to solve the same number story with manipulatives and on a ten frame.  I make sure to model how I want the students to complete their number story.  I include a picture that clearly represents the subtraction.  I also include the equation at the bottom of the page.  While writing equations is not required in kindergarten, it is encouraged, so I set students up with the opportunity to write an equation for their number story. 
You are going to get your own "If You Were A Minus Sign" Book that you started yesterday.  Your book has four pages.  Today we are only going to work on the second page.  You can begin as soon as you have your book.

I walk around and make sure that students have come up with a number story and are drawing it and writing their equations.  I have ten frames and manipulatives available for who want to use those to represent the number story.  If students use the manipulatives, I take a picture of their work and add it to their book after I print the picture.


I got the idea for this activity from Mrs. Ricca's Kindergarten.  The "If You Were A Minus Sign" student book that I am using in this lesson is available as a free download from her blog.


20 minutes

The centers for this week are:


I am not sure if or for how long I will pull groups today.  I anticipate that some students will need help with their number stories and that some may just take longer on this task than our usual independent work.  I circulate to help students with their number stories and to make sure students are engaged and do not have any questions about how to complete the centers if they have finished their number story.   If time allows, I pull groups during centers and work with them depending on the time they need (5 - 10 minutes).

Today I am focusing on subtraction with all of the groups.  While my students are doing well on our subtraction lessons and centers, as we near the end of unit assessment, I would like to observe them more closely as their work through word problems.  I verbally give the group a word problem.  I have them solve it using manipulatives and write the equation.  With students who are able to do this easily, I also have them try with drawing pictures instead of manipulatives.

Prior to clean up, I check in with each table to see how the centers are going.  My students continue to struggle with getting cleaned up quickly and quietly after centers.  I have been using counting down from 20 slowly instead of a clean up song.  Counting backwards is as critical as counting up. Students need to be able to know the number that comes before, as well as after, any given number (w/i 10, w/i 20, etc.). Counting back is a critical strategy for subtraction.

The students like to count backwards with me as they clean up and I can lengthen or reduce the clean up time based on how students are doing and how much time we have.


10 minutes

To close, I put a student's book on the document camera and project it on the SMARTBoard and have the student explain their work.  I choose one student who clearly represented subtraction in their picture and wrote a correct equation.  I mention positive things noticed during centers as well as something that needs to be better next time. 

I review what we did during our whole group lesson.  "Today we learned talked about subtraction number stories and working on creating our own.  Tomorrow we will continue to work on our "If I Were A Minus Sign" books by creating another number story."