2.7.C
The Standard
represent and solve addition and subtraction word problems where unknowns may be any one of the terms in the problem
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students solve addition and subtraction stories when the missing number can be the start, the change, or the result. They use objects, drawings, or equations to show how the quantities relate.
What Mastery Looks Like
- Students identify what is unknown, choose addition or subtraction, and write a matching equation with a box or symbol. They solve accurately and explain how their model matches the story.
Common Misconceptions
- Students may add whenever they see “more” or subtract whenever they see “left.” They may also place the unknown only after the equal sign or confuse the starting amount with the result.
How to Assess It
- Give this exit ticket: “Some birds sat on a fence. 7 flew away, and 9 remained. How many birds were there at first?” Ask for a drawing, equation, and answer.
Lesson moves
Ways to Teach It
Use counters and cups to model hidden starting amounts, missing changes, and unknown results, then record each model with an equation.
Ask students to explain how 8 + □ = 13 and 13 − 8 = □ can represent the same story.
Play equation match by pairing word problem cards with equations that show the unknown in different positions.
Use a classroom supply problem, such as finding how many pencils were in a box before some were handed out.
Keep exploring
Related Standards
- 1.3.B
use objects and pictorial models to solve word problems involving joining, separating, and comparing sets within 20 and unknowns as any one of the terms in the ...
- 1.5.D
represent word problems involving addition and subtraction of whole numbers up to 20 using concrete and pictorial models and number sentences
- 1.5.F
determine the unknown whole number in an addition or subtraction equation when the unknown may be any one of the three or four terms in the equation
- 2.4.C
solve one-step and multi-step word problems involving addition and subtraction within 1,000 using a variety of strategies based on place value, including algori...
Turn this exact standard into a lesson
Grade, subject, topic, and the complete standard are prefilled. Create one free, no account needed.