# ALEX Lesson Plan

## Add, Subtract, and Multiply Matrices

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This lesson provided by:
 Author: Morgan Boyd System: Dothan City School: Honeysuckle Middle School
General Lesson Information
 Lesson Plan ID: 35674 Title: Add, Subtract, and Multiply Matrices Overview/Annotation: The lesson will introduce the concept of a matrix. The matrix is labeled by its rows and columns. This lesson will teach the concept of adding, subtracting, scalar multiplication, and multiplication of matrices. This lesson will be a prerequisite for solving systems of equations with matrices.This lesson results from the ALEX Resource Gap Project.
Associated Standards and Objectives
Content Standard(s):
 Mathematics MA2015 (2015) Grade: 9-12 Algebra II 9 ) (+) Add, subtract, and multiply matrices of appropriate dimensions. [N-VM8] Mathematics MA2015 (2015) Grade: 9-12 Algebra II with Trigonometry 9 ) (+) Add, subtract, and multiply matrices of appropriate dimensions. [N-VM8]

Local/National Standards:

Primary Learning Objective(s):

The student will be able to multiply a scalar by a matrix.

The student will be able to add matrices.

The student will be able to subtract matrices.

The student will be able to multiply matrices.

Preparation Information
 Total Duration: 61 to 90 Minutes Materials and Resources: PencilNotebookAlgebra II textbook (student and teacher edition)Calculator (graphing, if available)Bell Ringer Matrices (in attachments)Website for scalar multiplication with matrices:https://www.khanacademy.org/math/precalculus/precalc-matrices/multiplying-matrices-by-scalars/v/scalar-multiplicationWebsite for adding and subtracting matrices:https://www.khanacademy.org/math/precalculus/precalc-matrices/adding-and-subtracting-matrices/v/matrix-addition-and-subtraction-1Website for multiplying matrices:https://www.khanacademy.org/math/precalculus/precalc-matrices/multiplying-matrices-by-matrices/v/matrix-multiplication-introWorksheets to be copied for all students:Exit SlipAdding and Subtractinghttp://www.math-aids.com/cgi/pdf_viewer_12.cgi?script_name=algebra2_matrices_basicOps.pl&elemType=0&undefType=2&language=0&memo=&answer=1&x=75&y=24Multiplying Matriceshttp://www.math-aids.com/cgi/pdf_viewer_12.cgi?script_name=algebra2_matrices_matrMult.pl&elemType=0&undefType=2&language=0&memo=&answer=1&x=122&y=18Worksheet for Accelerated Students: copy as neededhttps://www.mathworksheets4kids.com/matrices/multiplication/18.pdf Technology Resources Needed: Desktop computer/Interactive WhiteboardGraphing Calculator, if available Background/Preparation: Teacher:The teacher will need to preview the videos and other materials on the Khan Academy website. The website has interactive sessions after the introduction. The teacher can pick and choose the problems and material according to the skill level of the class.Student:The student needs to know that matrices are labeled by their dimensions like pieces of wood. An example is a 4 x 8 piece of plywood. The student needs to be able to write linear equations in standard form.
Procedures/Activities: