Primary Type: Formative Assessment
Status: Published
This is a resource from CPALMS (www.cpalms.org) where all educators go for bright ideas!
Resource ID#: 55564
Solving Literal Equations
Students are given three literal equations, each involving three variables and either addition or subtraction, and are asked to solve each equation for
a specific variable.
Subject(s): Mathematics
Grade Level(s): 9, 10, 11, 12
Intended Audience: Educators
Freely Available: Yes
Keywords: MFAS, literal equations, solving, rearranging, variable
Resource Collection: MFAS Formative Assessments
ATTACHMENTS
MFAS_SolvingLiteralEquations_Worksheet.docx
FORMATIVE ASSESSMENT TASK
Instructions for Implementing the Task
This task can be implemented individually, with small groups, or with the whole class.
1. The teacher asks the student to complete the problems on the Solving Literal Equations worksheet.
2. The teacher asks follow-up questions as needed.
TASK RUBRIC
Getting Started
Misconception/Error
The student is unable to apply strategies used in solving equations when rewriting formulas.
Examples of Student Work at this Level
The student does not understand how to apply inverse properties in literal equations. The student may:
Substitute numbers into the formulas and compute.
Manipulate symbols without any mathematical justification.
page 1 of 3 Questions Eliciting Thinking
What is the question asking you to do? If all the other variables were numbers, what would you do first? Second?
To solve literal equations, we apply the order of operations backwards. How might you do that with these problems?
When we solve equations, whatever we do to one side of the equal sign, must be done to the other side to keep it ‘balanced.’ Does your work adhere to this rule? Where
is your equation off-balance? Can you identify your mistake?
Instructional Implications
Review the four basic operations (i.e., add, subtract, multiply, and divide) and give the student the opportunity to determine the inverse of each. Provide feedback as
needed.
Review the reasoning that is used in solving equations and assist the student in applying it to formulas. Begin with simple three-variable formulas that require only one step
to solve, and then introduce the student to two-step and multistep problems.
Making Progress
Misconception/Error
The student partially applies inverse operations appropriately but makes mistakes.
Examples of Student Work at this Level
The student:
Determines the correct operation to use to manipulate a targeted variable but makes sign errors in his or her work.
Understands the need to multiply each side of the equation by -1 but does so incorrectly.
Questions Eliciting Thinking
Is it always necessary to have the variable you are solving for on the left side of the equal sign? Can you solve questions one and two in just one step by leaving the variable
on the right side of the equal sign?
For the last equation, did you solve for
or
? What might you do to solve for
?
For question number three, your work indicates that you are multiplying both sides by -1. That is a correct process, but there is a mistake in your multiplication. Can you
identify your mistake?
Instructional Implications
page 2 of 3 Give the student other multistep literal equations involving addition and subtraction. Remind the student to use parentheses to ‘group’ the terms when multiplying both
sides of an equation by negative one. Provide feedback as necessary.
If necessary, suggest to the student that he or she circle the variable to be isolated and pretend all other variables are numbers in an equation. This may help the student
to select the appropriate inverse operations.
Got It
Misconception/Error
The student provides complete and correct responses to all components of the task.
Examples of Student Work at this Level
The student shows mathematically correct work and conclusions such as:
1.
=d+
, or
=
+d
2. b = a - c, or b = -c + a
3.
= -d +
, or
=
-d
Questions Eliciting Thinking
For the third equation, you correctly multiplied both sides of the equation by -1. Are the parentheses necessary? Why or why not?
To get your same answer for question one, could you have subtracted
from both sides of the equation as an alternate first step? Why or why not?
Instructional Implications
Challenge the student to find as many other strategies as possible for solving each equation for the indicated variable.
ACCOMMODATIONS & RECOMMENDATIONS
Special Materials Needed:
Solving Literal Equations Worksheet
SOURCE AND ACCESS INFORMATION
Contributed by: MFAS FCRSTEM
Name of Author/Source: MFAS FCRSTEM
District/Organization of Contributor(s): Okaloosa
Is this Resource freely Available? Yes
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
MAFS.912.A-CED.1.4:
Description
Rearrange formulas to highlight a quantity of interest, using the same reasoning as in solving equations. For example,
rearrange Ohm’s law V = IR to highlight resistance R. ★
page 3 of 3