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Examples
Example: 9+?=12Example: 
Example: ?-4=8
Clarifications
Clarification 1: Instruction begins the development of algebraic thinking skills where the symbolic representation of the unknown uses any symbol other than a letter.Clarification 2: Problems include the unknown on either side of the equal sign.
Clarification 3: Addition and subtraction are limited to sums within 20 and related subtraction facts. Refer to Situations Involving Operations with Numbers (Appendix A).
Benchmark Instructional Guide
Connecting Benchmarks/Horizontal Alignment
Terms from the K-12 Glossary
- Equal Sign
- Equation
- Expression
Vertical Alignment
Previous Benchmarks
Next Benchmarks
Purpose and Instructional Strategies
The purpose of this benchmark is for students to deepen their understanding of the equal sign and build relational thinking when looking at equations. In Kindergarten, students used objects or drawings to explain why addition or subtraction equations are true or false (MTR.5.1).- Instruction includes helping students to begin to develop the algebraic skill of determining a number that makes an equation true.
- Within this benchmark, students are expected to understand the meaning of the equal sign and how equations are used to model mathematical situations and problems.
- Instruction includes an unknown value in any position (MTR.2.1).
- Instruction includes presenting equations in different forms such as a + b = c or c = a + b (MTR.2.1).
- Instruction may include the use of a balance scale representation or bar model to help
students understand how to write equations (MTR.2.1, MTR.5.1).
- For example, a balance model and a “bar model” for 8 = 5 + 3 are shown below
Common Misconceptions or Errors
- Students may not understand that they can use addition to figure out a subtraction equation or use a subtraction to figure out an addition equation. In these cases, ask students to find the related facts for a given problem.
Strategies to Support Tiered Instruction
- Teacher provides opportunities to use number bonds to develop an understanding of fact families and inverse relationships.
- For example, students create a number bond for the number 9. Students then write the fact families for the number 9. Discussion should be focused on how the fact families are related and how knowing the addition facts can help the students solve a subtraction problem.
- Teacher models solving problems that highlight the relationship between addition and subtraction using a linear ten frame. Then, students use two different colors to shade the addend on the ten frame.
- Example:
- Students write the addition fact that is represented on the ten frame 5 + 3 = 8.
- Students then subtract 3 from 8 by folding under the three “orange” blocks.
- Students are left with the 5 “blue” blocks, so 8 – 3 = 5.
- Students should practice with multiple addition facts. Discussion should be focused on the relationship between addition and subtraction.
Instructional Tasks
Instructional Task 1 (MTR.2.1)
Annette says the missing number for 18 − __= 14 is 8. Jessica says the missing number is 4. Who is correct? Use numbers, pictures and/or words to show your thinking.
Instructional Task 2 (MTR.2.1, MTR.4.1)
Emelio needs to find the missing number in the following number sentence:__ − 7 = 9. Draw a picture to show Emelio how he could find the missing number. Then describe how you found the missing number.
Instructional Task 3 (MTR.3.1)
What missing number would balance the equation 10 = 7 + __?
Instructional Items
Instructional Item 1
Which of the following equations are true with an unknown value equal to 8?- a.19− __=9
- b.18− __=10
- c. __= 20 − 8
- d. __=2+6
- e. 4+5= __
Instructional Item 2
What is the missing addend in the equation 15 = __ + 6?a. 15
b. 10
c. 9
d. 5
Instructional Item 3
What addition equation could help to determine the unknown in the equation 13 = __ − 4?a. 11+2=13
b. 10+4=14
c. 13+4=17
d. 4+8=12
*The strategies, tasks and items included in the B1G-M are examples and should not be considered comprehensive.
Related Courses
Related Access Points
Related Resources
Formative Assessments
Lesson Plans
Perspectives Video: Teaching Idea
Problem-Solving Task
MFAS Formative Assessments
Students are given equations with a missing number and asked to find the missing number.
Students are asked to find the unknown in three different equations and explain their reasoning.
Students are read a word problem and given an equation that matches the problem, and then asked to solve for the unknown in the equation.
Student Resources
Problem-Solving Task
This task asks students to solve addition and subtraction equations with different structures so that they are able to see the connections between addition and subtraction more easily. Examples should be presented with the the sum or difference on either side of the equal sign in order to dispel the notion that = means "compute."
Type: Problem-Solving Task
Parent Resources
Problem-Solving Task
This task asks students to solve addition and subtraction equations with different structures so that they are able to see the connections between addition and subtraction more easily. Examples should be presented with the the sum or difference on either side of the equal sign in order to dispel the notion that = means "compute."
Type: Problem-Solving Task
