Use addition and subtraction within 20 to solve word problems^{1} involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem (^{1}Students are not required to independently read the word problems.) (Standard #: MAFS.1.OA.1.1)

### Other Resources

In this tutorial video from Khan Academy, a word problem is solved with unit cubes, as well as with a missing addend addition equation and a subtraction equation.

Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Tutorial

In this tutorial video from Khan Academy, explore place value relationships with tens and ones within 20.

Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Tutorial

In this tutorial, you will learn how to solve a result unknown word problems: 10 - 2 = ?.

Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Tutorial

This virtual manipulative can be used to picture whole number operations, addition, subtraction, multiplication and division, carried out on a number line.

Subject Area(s): Mathematics

Grade Level(s): 1, 2, 3

Primary Resource Type: Educational Software / Tool

These problems explicitly describe one-to-one correspondences without using comparison language. Such problems are easier for students to solve than problems that use comparison language such as "How many more?" or "How many fewer."

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Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Problem-Solving Task

This task represents the Put Together/Take Apart with both addends unknown context for addition and subtraction. Once a student finds one correct answer, he/she can be encouraged to find another. Ask the student to use objects, pictures, or equations to represent each answer.

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Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Problem-Solving Task

Students may use either addition or subtraction to solve these types of word problems, with addition related to the action of putting together and subtraction related to the action of taking apart. Depending on how students think about these word problems, either is appropriate for the "addend unknown" problems. Seeing it both ways emphasizes the relationship between addition and subtraction.

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Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Problem-Solving Task

This task includes three different problem types using the "Add To" context with a discrete quantity.

Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Problem-Solving Task

Students benefit from encountering one problem type limited to small numbers and to develop strategies for that type of problem before encountering mixed sets of problems and larger numbers that distract the student from the problem itself. Over time they will be able to distinguish between types of problems in mixed sets and apply the appropriate strategy to solve each.

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Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Problem-Solving Task

The purpose of this task is for students to gain a better understanding of measurements with the example being the growth of a pet snake.

Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Problem-Solving Task

This task could be used for either instructional or assessment purposes, depending on where students are in their understanding of addition and how the teacher supports them. The solution shown is very terse; students' solution strategies are likely to be much more varied.

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Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Problem-Solving Task

These task types represent the Take From contexts for addition and subtraction. This task includes the three different problem types using the Take From context: result unknown, change unknown, and start unknown. Students need experience and practice with all three types.

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Subject Area(s): Mathematics

Grade Level(s): 1

Primary Resource Type: Problem-Solving Task

This interactive Flash applet helps children understand the "take away" model of subtraction. Users choose starting numbers from within 10 or 20. A group of rabbits appears and the user is asked how many will remain if a certain number run away. Mousing over a clue button dims the number of runaways. After selecting the correct remainder, the rabbits run away, and the applet displays the number model and the word sentence that represent the problem. [Available for iPad and iPhone in the iTunes AppStore.]

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Subject Area(s): Mathematics

Grade Level(s): K, 1

Primary Resource Type: Virtual Manipulative

A versatile tool that can be used to illustrate the operations of addition, subtraction, multiplication, and division.

Subject Area(s): Mathematics

Grade Level(s): 1, 2, 3, 6

Primary Resource Type: Virtual Manipulative