Primary Standards:

MAFS.1.OA.4.7 Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false. For example, which of the following equations are true and which are false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.

MAFS.1.OA.4.8 Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ?= 11, 5 = ? – 3, 6 + 6 = ?.

Connecting Standards:

MAFS.1.OA.3.6 Add and subtract within 20, demonstrating fluency for addition and subtraction within 10.

Content Knowledge:

Before this Unit, students will have worked with equations and solving for unknowns in equations.  This Unit makes the explicit transition from experiences with concrete materials and pictorial representations to more abstract models and symbols.  However, students may still use objects and pictures to justify their solutions, and should be encouraged to do so, though the goal is that students are able to understand the concept of equality, as well as use number relations.

Some students may develop the misconception that the equal sign indicates the answer comes next.  Students in this Unit should have experiences that reinforce that the equal sign indicated both sides of the equation represent the same amount.  Once students understand the meaning of the equal sign, they should determine if given equations are true or false.  Students should work with examples of equations in all orientations, one operation on either side (8 = 7 + 1 or 7 + 1 = 8), operations on both sides (4 + 4 = 3 + 5), and no operations (7 = 7).

Students in this Unit will also work on finding the value of unknowns in an equation.  Unknowns should be shown using different, alternating symbols such as a question mark, a box, or a blank line.  This helps students become comfortable in seeing the unknown in various ways.  Working with solving for unknowns with three related numbers will build upon students’ work with operations and fluency in prior Units.  Students should solve for the unknown in various positions and be asked to explain and justify how they found the unknown value.  Though this concept may relate to the topic of fact families, it is important to listen to each student’s reasoning for the equations and to understand that just writing fact families without thought to the context is not nurturing thinking and understanding of the solving unknowns.


GCG 1 – Learning Goal: As a Mathematician, I will be able to determine if equations are True or False (within 20)

  • Step 1: Understand the equal sign indicates that both sides of the equation are the same value within 20 (using models, symbols and numbers)
  • Step 2: Use symbols (+, -, and =) to write equivalent expressions as equations within 20
  • Step 3: Identify which equations are true and which equations are false within 20 (justify reasoning)

GCG 2 – Learning Goal: As a Mathematician, I will be able to Solve for Unknowns  (within 20)

  • Step 1: Solve for unknowns in an equation using concrete tools or drawings (within 20)
  • Step 2: Solve for unknowns in an equation (within 20)
  • Step 3: Solve for Unknowns using Word Problems (within 20)