1.OA.D.8 - About the Math, Learning Targets, and Increasing Rigor
Grade 1 Number Concepts
1.OA.D.8
Full Standard
Determine the unknown whole number in an addition or subtraction equation relating to 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 = ?.
Measurement Topic
This standard is reported on the report card in these quarters as follows:
| Quarter 1 | Quarter 2 | Quarter 3 | Quarter 4 |
|---|---|---|---|
|
|
|
Report Card Measurement Topic: Demonstrates understanding of addition.
Report Card Measurement Topic: Demonstrates understanding of subtraction. |
|
| Quarter 1 | Quarter 2 | Quarter 3 | Quarter 4 |
|---|---|---|---|
|
|
|
Report Card Measurement Topic: Demonstrates understanding of addition.
Report Card Measurement Topic: Demonstrates understanding of subtraction. |
|
About the Math
Skills and concepts below are learning goals for this standard.
This standard is critical in developing students' problem-solving skills, algebraic foundations, and understanding of addition and subtraction.
- Determine the unknown in an addition equation.
- Determine the unknown in a subtraction equation.
These learning targets are not about the procedural finding of an unknown in an addition or subtraction equation. The learning targets are grounded in the understanding of the meaning of the equal sign and the relationship between operations. Students should leverage understanding of part-part-whole relationships to write and find the unknown in an equation. This standard is closely related to others including that which is related to problem solving. This concept is an extension of the decomposing of numbers and students will use their understanding of decomposition of numbers when finding the missing part.
- Explain how an unknown in an equation was determined using physical models, drawings, number lines, and/or number charts.
Students should begin work with this standard by connecting symbolic representations to physical models, drawings, number charts, and/or number lines. Students should also connect these representations to the problems being solved as well as the equations that reflect the models and the problems.
Essential vocabulary for this standard includes equation and unknown. (online dictionary Links to an external site., HCPSS Vocabulary Cards Download HCPSS Vocabulary Cards).
Progression of Standard within Grade 1
This progression informs how to develop the standard within the grade level. This progression is provided by HCPSS Elementary Mathematics.
| Quarter 1 | Quarter 2 | Quarter 3 | Quarter 4 |
|---|---|---|---|
|
* Apply to properties and facts. |
Progression of this Standard Across Grades
This progression is informed by the Achieve the Core Coherence Map Links to an external site.. Information is not the complete standard.
| Grade 4 | |
|---|---|
|
This concept is not taught prior to grade 1. |
|
Back to Top
TASKS
These tasks can be used with small group or whole group instruction.
- Print Beginning, Middle, End Download Beginning, Middle, End organizers for each of your students. Tell them at recess you saw 3 friends go to the blacktop. Some more joined them and then there were 5 kids at the blacktop. Ask "what is the question I was thinking?" (How many joined them on the blacktop?) Tell you don't know how to figure this question out because it seems different than other problems you have solved. Explain you are going to use an organizer to help you figure out the beginning middle, and end of the story problem. Ask what is the problem about? What happened at the beginning of the problem (3 kids on blacktop) Middle (some joined) end (there were 5 kids on the blacktop). If we know "some more friends joined them" do we think we are adding or subtracting? Why? Under the middle section record +? to show that is the unknown. Ask what seems different about this problem? (? not at the end) What could we do to figure out what goes with 3 to get to 5? Have students share out ideas (use counters, number paths, count on, etc.) and let them solve it. Debrief and have students share out how they solved it. Continue to pose problems within 10 where the beginning or middle is missing (addition and subtraction) to use the organizer to help understand the context of what is going on in the problem.
- Use your number balances or bucket balances again to show equality in equations. (virtual one here Links to an external site. if you can't find in your building) write the equation 4 + ? = 9 on the board. Ask how they think we could use the number balance to solve this problem. Remind to show equality it needs to be balanced. Let them use the balances to see what number they need to hang a weight on with 4 to make it balance with 9. When they see it is 5 ask if they could show it using another tool. (number line, counters) and give them time to try to show that 4 + 5 more makes 9. Continue practicing with the number balance and other tools to make sense of solving for the unknown in an equation.
- Get out counters for students to use and have a large number line to 20 on the floor. Tell them that there were 10 brownies on a plate and your brother came by and ate some and now there were 7 brownies on the plate. Repeat and discuss what is happening in this problem. Ask how could we use a number line to help us solve this problem? What is happening in the beginning of the problem? (There were 10 brownies on a plate) Have a student come up and and stand on 10 as you write 10 on the board. Ask what happens next? (Your brother ate some. If someone eats are we going to have more or less brownies? So should we add or subtract? Then write -? on the board. Ask: What happens at the end? There are 7 brownies left. How could we show this on the number line? (Have the student hop to 7) How many hops did he make? So how many brownies did your brother eat? Then ask how could we show this with counters? Let them model with counters as well and explain their thinking. Continue practicing with the unknown moving positions if there is time.
- I am thinking of two numbers on the number line that have a difference of 5. What could the two numbers be? How do you know?
- If the sum of two numbers is 13, what could the two addends be? How do you know?
- Use the digits 3, 4, 5, 6 & 7 to make the following equations true. Each digit may be used only once. (_ + 6 = 12, 5 - _ = 2, 4 = _ - 3, 6 = 2 + _13 - ___ = 8)
- A ribbon is 14 inches long. Jan used some ribbon to wrap a gift. How much ribbon could be left?. How many inches of ribbon did Jan use? Write a number sentence show how you solved the problem.
SLIDE-BASED TASKS
These links are HCPSS created instructional tasks. These tasks are provided in Google slides. These tasks should be used for inspiration and resources, but instruction should start with students having the opportunity to engage with the math first (often involving physical and/or visual models) followed by discussion and explicit instruction to ensure student understanding.
Module 10 • Three Addends and the Associative Property
Determine the unknown in an addition/subtraction equation:
Additional Tasks
These links provide instructional ideas connected to this standard.
- Find the Missing Number Links to an external site.(Illustrative Math)
- Kiri's Mathematics Match Game ( Links to an external site.Illustrative Math)
- Who Stole the Cookies Download Who Stole the Cookies (Utah Core Academy)
- Missing Cookies Download Missing Cookies (Utah Core Academy)
- The Missing Number Mystery Download The Missing Number Mystery (Utah Core Academy Lesson)
- Field Trip Download Field Trip (Utah Core Academy Lesson)
- Vacation Download Vacation (Utah Core Academy Lesson)
- Number Sentences Download Number Sentences (Utah Core Academy Lesson)
- Block Pounds Links to an external site. (NCTM Illuminations Lesson)
- Try For Five Links to an external site. (NCTM Illuminations Lesson)
Tasks From Print Resources
These publications have been provided for each school. They are typically stored in team closets or the media center. Check with your team leader if you cannot find them.
| Book Thumbnail | Book Title | Grade | Pages |
|---|---|---|---|
| Teaching Student-Centered Mathematics | K-3 |
Missing-Part Cards, Activity 2.19, Page 50 |
|
|
Groundworks Algebraic Thinking |
1 | (64-87) | |
|
Read It, Draw It, Solve It
|
1 | (140, 158, 160, 162) | |
|
Math Intervention: Building Number Power |
K-2 |
(111-121) |
Back to Top
Centers
These print resources can be used during independent or center time. These resources could also be used as lesson seeds.
- What's Missing? Download What's Missing? ( HCPSS-adapted resource)
- Remover Download Remover (HCPSS-adapted resource/game)
- Determine the Unknown Links to an external site.
Independent Practice/HOmEWoRK/Assessment
These resource sheets can be used for independent practice, homework, or assessment. They are intended to reinforce procedures and concepts. They should not be used as a source of direct instruction or whole-group practice.
- Determine the Unknown in Addition or Subtraction Equations Links to an external site.
- Determine the Unknown in Addition Equations Links to an external site.
- Determine the Unknown in Addition & Subtraction Equations Links to an external site.
- Determine the Unknown in Addition & Subtraction Equations_2 Links to an external site.
- Determine the Unknown in Addition & Subtraction Equations_3 Links to an external site.
- Evaluate Addition & Subtraction Equations with Unknowns Links to an external site.
- Evaluate Addition & Subtraction Equations with Unknowns_2 Links to an external site.
Back to Top
Full Standard
Determine the unknown whole number in an addition or subtraction equation relating to 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 = ?.
Measurement Topic
The standard is reported on the report card through these measurement topics. Expand the measurement topic for a description of what students who meet expectation are able to do.
First Grade Students Learning First Grade Standards by Measurement Topic
Demonstrates understanding of addition
Quarter 3
- Determine the unknown in an addition equation.
- Explain how the unknown in an addition equation was determined using physical models, drawings, charts, number lines and/or equations.
Demonstrates understanding of subtraction
Quarter 3
- Determine the unknown in a subtraction equation.
- Explain how the unknown in a subtraction equation was determined using physical models, drawings, charts, number lines, and/or equations.
Kindergarten Students Learning 1st Grade Standards by Measurement Topic
Demonstrates understanding of addition
Quarter 3
- Determine the unknown in an addition equation.
- Explain how the unknown in an addition equation was determined using physical models, drawings, charts, number lines and/or equations.
Demonstrates understanding of subtraction
Quarter 3
- Determine the unknown in a subtraction equation.
- Explain how the unknown in a subtraction equation was determined using physical models, drawings, charts, number lines, and/or equations.
1OA8 Anecdotal Data Collection Tool for Addition Links to an external site.
1OA8 Anecdotal Data Collection Tool for Subtraction Links to an external site.
Visit the SBIR (Standards Based Instruction and Reporting) page in Course Essentials for more information and clarification.
Rubric (for thinking and reasoning evidence)
Use this rubric for observation and constructed responses (tasks that require explanation, justification, and/or representation).
Rubric for Tasks (pdf) Links to an external site.
Exemplars for this standard (if available)
These samples are examples of what it might look like for a student who MEETS EXPECTATIONS, is MAKING PROGRESS, and/or is MAKING LIMITED/NO PROGRESS.
Back to Top
This course content is offered under a CC Attribution Non-Commercial Share Alike
Links to an external site. license. Content in this course can be considered under this license unless otherwise noted.