1.OA.3 Apply properties of operations as
strategies to add and subtract. Examples:
If 8 + 3 = 11 is known, then 3 + 8 = 11 is
also known. (Commutative property of addition.)
To add 2 + 6 + 4, the second two numbers can
be added to make a ten, so 2 + 6 + 4 = 2 + 10
= 12. (Associative property of addition.) (Students
need not use formal terms for these properties.)

1.OA.6 Add and subtract within 20, demonstrating
fluency for addition and subtraction within 10.
Use strategies such as counting on; making
ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14);
decomposing a number leading to a ten (e.g.,
13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the
relationship between addition and subtraction (e.g.,
knowing that 8 + 4 = 12, one knows 12 – 8 = 4);
and creating equivalent but easier or known sums
(e.g., adding 6 + 7 by creating the known equivalent
6 + 6 + 1 = 12 + 1 = 13).

1.OA.1 Use addition and subtraction within 20 to
solve word problems 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.OA.3 Apply properties of operations as strategies
to add and subtract. Examples: If 8 + 3 = 11 is
known, then 3 + 8 = 11 is also known. (Commutative
property of addition.) To add 2 + 6 + 4, the second
two numbers can be added to make a ten,
so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of
addition.) (Students need not use formal terms for
these properties.)
1.OA.5 Relate counting to addition and subtraction
(e.g., by counting on 2 to add 2).
1.OA.7 Understand the meaning of the
equal sign, and determine if equations involving
addition and subtraction are true or false. For
example, which of the following equations are
true and which are false? 6 = 6, 7 = 8 – 1,
5 + 2 = 2 + 5, 4 + 1 = 5 + 2.

1.OA.1 Use addition and subtraction within 20 to
solve word problems 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.OA.4 Understand subtraction as an
unknown-addend problem. For example, subtract
10 – 8 by finding the number that makes 10 when
added to 8.
1.OA.5 Relate counting to addition and subtraction
(e.g., by counting on 2 to add 2).
1.OA.6 Add and subtract within 20, demonstrating
fluency for addition and subtraction within 10. Use
strategies such as counting on; making ten
(e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14);
decomposing a number leading to a ten
(e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the
relationship between addition and subtraction (e.g.,
knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and
creating equivalent but easier or known sums (e.g.,
adding 6 + 7 by creating the known equivalent
6 + 6 + 1 = 12 + 1 = 13).
1.OA.7 Understand the meaning of the equal sign,
and determine if equations involving addition and
subtraction are true or false. For example, which
of the following equations are true and which are
false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.
1.OA.8 Determine the unknown whole number in an
addition or subtraction equation relating 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 = ＿.