Subtracting from 8
Lesson 13 of 19
Objective: Students will be to able solve subtraction equations.
Problem of the Day
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:
Solve. Draw a picture to show how you found your answer. 5 - 2 =
For this problem, I created a Notebook file with a lot of open space for students to draw. I also put an equation for the students to solve. If you do not have a SMARTBoard, you can use the PDF file. You could also have the students solve the problem by drawing a picture on paper or the board or using manipulatives.I have one student come up and work on this problem. I remind student to check his or her work when they are finished and have the class tell if they agree or disagree by showing a thumbs up or thumbs down. I am also looking for students to explain how they solved the problem (Mathematical Practice 3: Construct viable arguments and critique the reasoning of others).
Presentation of Lesson
I start this lesson by writing the number 8 on the board.
What number is this? Today we are going to look at what happens when we take away from 8. Let's start by using what we already have on our bodies that can help us count. Put up 8 fingers. If I have 8 and I take away 0, how many fingers do I still have up?
I show it on my fingers and write the equation on the board. 8 - 0 = 8. I have students model with their fingers and I write the other possible equations 8-1, 8-2, 8-3 8-4, 8-5, 8-6, 8-7 and 8-8 on the board.
We are going to work on this paper together. When you get to your seat, do not touch your cup of counters. You need to get out a pencil and put your name on your paper. When your name is on your paper hold your pencil in the air, that will let me know that you are ready to start.
I use the procedures outlined here on the Paper Procedures. Prior to this lesson, I placed a plastic cup at each students' place containing eight color tiles.
Use your color tiles to model each equation. Write the numbers to complete the equations.
The first thing the directions tell you to do is use the color tiles to model each equation. You will notice that the last question does not have an equation to model. For this question, you will need to use the color tiles to come up with your own way to subtract from 8.
We work through the first 5 questions together. For the last question, I show one way to do it on the SMARTBoard. I then allow the students to come up with their own way. I walk around and make sure that students are correctly counting writing their equations. When students are finished with their paper, they can put it in the basket and get their center.
The centers for this week are:
- Monster Subtraction (Teacher Created Resource)
- Loosing Teeth Subtraction (Teacher Created Resource)
- Piggy Bank Subtraction (from Kindegarten Crayons)
- Domino Parking Lot (from Once Upon a First Grade Adventure)
- Critter Junction Subtraction on SMARTBoard/Computer (from MacMillan McGraw-Hill)
Today I am focusing on subtraction with all of the groups. I am using a work mat and action hero cutouts form KidSparkz. I give students an equation and have them solve it on the work mat using the action hero cutouts.
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.
To close, I put a student's paper on the document camera a project it on the SMART Board and have that student explain their work. I have the class read the equation using the words minus and equals. 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 about taking away from 8. Tomorrow we are going to continue this series of lessons where where we practice subtracting from a given number!"