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Overview of Oregon Common Core State Standards for 1st Grade
Mathematics  Grade 1
In Grade 1, instructional time should focus on four critical areas: (1) developing understanding of addition, subtraction, and strategies for addition and subtraction within 20; (2) developing understanding of whole number relationships and place value, including grouping in tens and ones; (3) developing understanding of linear measurement and measuring lengths as iterating length units; and (4) reasoning about attributes of, and composing and decomposing geometric shapes.
Critical Area #1
Developing understanding of addition, subtraction, and strategies for addition and subtraction within 20.
Students develop strategies for adding and subtracting whole numbers based on their prior work with small numbers. They use a variety of models, including discrete objects and lengthbased models (e.g., cubes connected to form lengths), to model addto, takefrom, puttogether, takeapart, and compare situations to develop meaning for the operations of addition and subtraction, and to develop strategies to solve arithmetic problems with these operations. Students understand connections between counting and addition and subtraction (e.g., adding two is the same as counting on two). They use properties of addition to add whole numbers and to create and use increasingly sophisticated strategies based on these properties (e.g., "making tens") to solve addition and subtraction problems within 20. By comparing a variety of solution strategies, children build their understanding of the relationship between addition and subtraction.
Critical Area #2
Developing understanding of whole number relationships and place value, including grouping in tens and ones.
Students develop, discuss, and use efficient, accurate, and generalizable methods to add within 100 and subtract multiples of 10. They compare whole numbers (at least to 100) to develop understanding of and solve problems involving their relative sizes. They think of whole numbers between 10 and 100 in terms of tens and ones (especially recognizing the numbers 11 to 19 as composed of a ten and some ones). Through activities that build number sense, they understand the order of the counting numbers and their relative magnitudes.
Critical Area #3
Developing understanding of linear measurement and measuring lengths as iterating length units.
Students develop an understanding of the meaning and processes of measurement, including underlying concepts such as iterating (the mental activity of building up the length of an object with equalsized units) and the transitivity principle for indirect measurement.(Students should apply the principle of transitivity of measurement to make indirect comparisons, but they need not use this technical term.)
Critical Area #4
Reasoning about attributes of, and composing and decomposing geometric shapes.
Students compose and decompose plane or solid figures (e.g., put two triangles together to make a quadrilateral) and build understanding of partwhole relationships as well as the properties of the original and composite shapes. As they combine shapes, they recognize them from different perspectives and orientations, describe their geometric attributes, and determine how they are alike and different, to develop the background for measurement and for initial understandings of properties such as congruence and symmetry.
How to read the grade level standards
Standards define what students should understand and be able to do.
Clusters are groups of related standards. Note that standards from different clusters may sometimes be closely related, because mathematics is a connected subject.
Domains are larger groups of related standards. Standards from different domains may sometimes be closely related.
Grade 1 Overview
A. Represent and solve problems involving addition and subtraction.
B. Understand and apply properties of operations and the relationship between addition and subtraction.
C. Add and subtract within 20.
D. Work with addition and subtraction equations.
E. Extend the counting sequence.
F. Understand place value.
G. Use place value understanding and properties of operations to add and subtract.
H. Measure lengths indirectly and by iterating length units.
I. Tell and write time.
J. Represent and interpret data.
K. Reason with shapes and their attributes.
Mathematical Practices 1.MP
The Standards for Mathematical Practice describe varieties of expertise that mathematics educators at all levels should seek to develop in their students.
1.MP.1 Make sense of problems and persevere in solving them.
1.MP.2 Reason abstractly and quantitatively.
1.MP.3 Construct viable arguments and critique the reasoning of others.
1.MP.4 Model with mathematics.
1.MP.5 Use appropriate tools strategically.
1.MP.6 Attend to precision.
1.MP.7 Look for and make use of structure.
1.MP.8 Look for and express regularity in repeated reasoning.
