Number Sense: Up to 30

Ages 4–6 · 10 minutes · Math

Build number sense for the numbers from 21 to 30

In this lesson, students will learn about the numbers from 21 to 30. They will get practice counting up to 30 using math cubes, monkeys, jelly beans, and shapes. They will explore representations of numbers up to 30 using ten rods and ten frames, and they will explore the concept of place value as we increase from 29 to 30.

Part of

Number Sense: 21–100

Standards alignment

Common Core State Standards

K.CC.A.1 — Count to 100 by ones and by tens.
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.B.2.a — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: 10 can be thought of as a bundle of ten ones — called a "ten."
1.NBT.B.2.c — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

Alabama

MA19.1.11 — Explain that the two digits of a two-digit number represent amounts of tens and ones.
MA19.1.11a — Identify a bundle of ten ones as a "ten."
MA19.1.11c — Identify the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 as one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
MA19.1.13a — Add a two-digit number and a one-digit number.
MA19.K.1 — Count forward orally from 0 to 100 by ones and by tens. Count backward orally from 10 to 0 by ones.

Alaska

1.CC.4 — Count a large quantity of objects by grouping into 10s and counting by 10s and 1s to find the quantity.
1.NBT.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90, refer to one, two, three, four, five, six, seven, eight or nine tens (and 0 ones).
K.CC.2 — Count forward beginning from a given number within the known sequence.
K.CC.4.c — Understand that each successive number name refers to a quantity that is one larger.

Arizona

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
K.CC.A.2 — Count forward from a given number other than one, within the known sequence (e.g., "Starting at the number 5, count up to 11.").
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

Arkansas

1.NPV.3 — Explain the place value of ones and tens in two-digit numbers, using concrete models, diagrams, numbers, or words.
1.NPV.4 — Read, write, and represent whole numbers up to 120, using concrete models or drawings, word form, base ten numerals, and expanded form.
K.NPV.1 — Count to 100 by ones and tens; count forward by ones from any given number up to 100.
1.CAR.4 — Use concrete models or drawings to add within 100, including a two-digit number and a one-digit number as well as a two-digit number and a multiple of ten; relate strategy used to a written expression or equation and explain reasoning.
1.NPV.1 — Count forward and back within 120 by ones and tens from any given whole number.

California

K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).

Colorado

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.A.1 — Count to 100 by ones and by tens.

Connecticut

K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.
1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.A.1 — Count to 100 by ones and by tens.
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."

Delaware

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

Florida

MA.1.NSO.1.3 — Compose and decompose two-digit numbers in multiple ways using tens and ones. Demonstrate each composition or decomposition with objects, drawings and expressions or equations.
MA.K.NSO.2.1 — Recite the number names to 100 by ones and by tens. Starting at a given number, count forward within 100 and backward within 20.
MA.1.NSO.2.3 — Identify the number that is one more, one less, ten more and ten less than a given two-digit number.
MA.1.NSO.2.4 — Explore the addition of a two-digit number and a one-digit number with sums to 100.

Georgia

K.NR.2 — Use count sequences within 100 to count forward and backward in sequence.
K.NR.2.1 — Count forward to 100 by tens and ones and backward from 20 by ones.
1.NR.1.2 — Explain that the two digits of a 2-digit number represent the amounts of tens and ones.
K.NR.2.2 — Count forward beginning from any number within 100 and count backward from any number within 20.

Hawaii

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
K.CC.A.1 — Count to 100 by ones and by tens.
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.B.2c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.B.4c — Understand that each successive number name refers to a quantity that is one larger.

Idaho

K.CC.A.2 — Starting at a given number, count forward within 100 and backward within 20.
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and zero ones).
K.CC.A.1 — Count to 100 by ones and by tens.
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger. Recognize the “one more” pattern of counting using objects.

Illinois

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

Indiana

K.NS.1 — Count to at least 100 by ones and tens. Count by one from any given number. (E)
1.NS.2 — Model place value concepts of two-digit numbers, multiples of 10, and equivalent forms of whole numbers using objects and drawings. (E)
K.NS.7 — Define and model a "ten" as a group of ten ones. Model equivalent forms of whole numbers from 10 to 20 as groups of tens and ones using objects and drawings. (E)
K.NS.3 — Say the number names in standard order when counting objects, pairing each object with one and only one number name and each number name with one and only one object. Understand that the last number name said describes the number of objects counted and that the number of objects is the same regardless of their arrangement or the order in which they were counted. Count out the number of objects, given a number from 1 to 20. (E)

Iowa

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases.
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.A.2 — Count forward beginning from any given number within the range of 0–100.
1.NBT.C.4 — Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

Kansas

1.NBT.1 — Count to 120 (recognizing growth and repeating patterns), starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral.
1.NBT.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.2.a — 10 can be thought of as a grouping of ten ones—called a “ten.”
K.CC.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).

Kentucky

KY.1.NBT.2 — Understand the two-digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
KY.K.CC.2 — Count forward beginning from a given number within the known sequence within 100 (instead of having to begin at 1).
KY.K.CC.4.c — Understand that each successive number name refers to a quantity that is one larger.
KY.1.NBT.2.a — 10 can be thought of as a bundle of ten ones — called a “ten.”
KY.1.NBT.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight or nine tens (and 0 ones).

Louisiana

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.A.1 — Count to 120, starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral.
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).

Maine

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1)
K.CC.B.4c — Understand that each successive number name refers to a quantity that is one larger. Recognize the one more pattern of counting using objects.
K.CC.A.1 — Count to 100 by ones and by tens

Maryland

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
1.NBT.C.4 — Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

Massachusetts

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
K.CC.A.1 — Count to 100 by ones and by tens.
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at one).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones—called a "ten."
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger. Recognize the one more pattern of counting using objects.

Michigan

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.
1.NBT.C.4 — Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

Minnesota

1.1.1.1 — Use place value to describe whole numbers between 10 and 100 in terms of tens and ones. For example: Recognize the numbers 21 to 29 as 2 tens and a particular number of ones.
K.1.1.2 — Read, write, and represent whole numbers from 0 to at least 31. Representations may include numerals, pictures, real objects and picture graphs, spoken words, and manipulatives such as connecting cubes. For example: Represent the number of students taking hot lunch with tally marks.
K.1.1.4 — Find a number that is 1 more or 1 less than a given number.
K.1.1.3 — Count, with and without objects, forward and backward to at least 20.

Mississippi

1.NBT.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.4.c — Understand that each successive number name refers to a quantity that is one larger.
K.CC.1 — Count to 100 by ones and by tens.

Missouri

1.NBT.A.1 — Understand that 10 can be thought of as a bundle of 10 ones – called a “ten”.
1.NBT.A.2 — Understand two-digit numbers are composed of ten(s) and one(s).
K.NS.B.7 — Demonstrate that each successive number name refers to a quantity that is one larger than the previous number.
K.NS.A.2 — Count forward beginning from a given number between 1 and 20.
K.NS.B.9 — Demonstrate that a number can be used to represent “how many” are in a set.

Montana

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
K.CC.A.1 — Count to 100 by ones and by tens.
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

Nebraska

1.N.3.a — Understand 10 as a bundle, collection, or (more abstractly) composition of ten ones and that the two digits of a two-digit number represent a composition of some tens and some ones.
K.N.2.b — Understand that each successive number name refers to a quantity that is one larger.
K.N.2.f — Count verbally in sequential order by ones and by tens to 100, making accurate decade transitions (e.g., 89 to 90). K.N.2.g Write and name numbers 0 to 20. Represent a number of objects with a written numeral 0 to 20.
1.N.3 — Base Ten: Students will represent and compare two-digit numbers to gain foundations for place value.
1.N.4.e — Add within 100, including adding a two-digit number and a one-digit number, adding a two-digit number and a multiple of ten, using concrete models, drawings, and strategies that reflect an understanding of place value, the relationship between addition and subtraction, and the properties of operations. Relate the strategy to a written method and explain the reasoning used to solve.

Nevada

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
K.CC.A.1 — Count to 100 by ones and by tens.
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

New Hampshire

K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

New Jersey

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: a. 10 can be thought of as a bundle of ten ones — called a “ten.” b. The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones. c. The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.B.4c — Understand that each successive number name refers to a quantity that is one larger.
1.NBT.C.4 — Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models (e.g., base ten blocks) or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
K.CC.A.1 — Count to 100 by ones and by tens.

New Mexico

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

New York

NY-1.NBT.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones.
NY-1.NBT.2.c — Understand the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
NY-K.CC.4.c — Understand the concept that each successive number name refers to a quantity that is one larger.
NY-1.NBT.2.a — Understand 10 can be thought of as a bundle of ten ones, called a "ten".
NY-K.CC.2 — Count to 100 by ones beginning from any given number (instead of beginning at 1).

North Carolina

NC.1.NBT.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. • Unitize by making a ten from a collection of ten ones. • Model the numbers from 11 to 19 as composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones. • Demonstrate that the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens, with 0 ones.
NC.K.CC.2 — Count forward beginning from a given number within the known sequence, instead of having to begin at 1.
NC.1.NBT.4 — Using concrete models or drawings, strategies based on place value, properties of operations, and explaining the reasoning used, add, within 100, in the following situations: • A two-digit number and a one-digit number • A two-digit number and a multiple of 10
NC.K.CC.1 — Know number names and recognize patterns in the counting sequence by: • Counting to 100 by ones. • Counting to 100 by tens.

North Dakota

1.NO.NBT.1 — Demonstrate that the two digits of a two-digit number represent a composition of some tens and some ones.
1.NO.CC.3 — Represent several objects with a written numeral up to 120.
1.NO.NBT.3 — Add within 100 using a two-digit number and a one-digit number. Use concrete models, drawings, and strategies that reflect an understanding of place value.
K.NO.CC.1 — Count verbally in sequential order by ones and tens to 100, making accurate decuple transitions (e.g., 89 to 90). Count verbally forward from any given number within 100.

Ohio

1.NBT.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: 10 can be thought of as a bundle of ten ones — called a “ten;” the numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones; and the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).

Oklahoma

1.N.1 — Count, compare, and represent whole numbers up to 100, with an emphasis on grouping in terms of tens and ones.
1.N.1.2 — Use concrete representations to describe whole numbers between 10 and 100 in terms of tens and ones. Know that 10 is equivalent to 10 ones and 100 is equivalent to 10 tens.
1.N.1.3 — Read, write, discuss, and represent whole numbers up to 100. Representations may include numerals, words, addition and subtraction, pictures, tally marks, number lines, and manipulatives.
1.N.1.4 — Count forward, with objects, from any given number up to 100 by 1s, 2s, 5s and 10s.

Oregon

1.NBT.B.2 — Understand 10 as a bundle of ten ones and that the two digits of a two-digit number represent amounts of tens and ones.
K.NCC.A.2 — Count forward beginning from a given number within 100 of a known sequence.
K.NCC.A.1 — Orally count to 100 by ones and by tens in sequential order.
MP7 — Look for and make use of structure.

Pennsylvania

CC.2.1.K.A.1 — Know number names and write and recite the count sequence.
CC.2.1.1.B.2 — Use place-value concepts to represent amounts of tens and ones and to compare two digit numbers.
CC.2.1.K.A.2 — Apply one-to-one correspondence to count the number of objects.

Rhode Island

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at one).
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.C.4 — Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger. Recognize the one more pattern of counting using objects

South Carolina

1.NSBT.2a — Understand place value through 99 by demonstrating that ten ones can be thought of as a bundle (group) called a “ten”.
1.NSBT.1c — Extend the number sequence to read, write and represent numbers to 100 using concrete models, standard form, and equations in expanded form.
1.NSBT.2b — Understand place value through 99 by demonstrating that the tens digit in a two-digit number represents the number of tens and the ones digit represents the number of ones.
1.NSBT.4a — Add through 99 using concrete models, drawings, and strategies based on place value to add a two-digit number and a one-digit number, understanding that sometimes it is necessary to compose a ten (regroup).
K.NS.2 — Count forward by ones beginning from any number less than 100.

South Dakota

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.C.4.a — Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
K.CC.A.2 — Count forward beginning from any given number within 100 (instead of having to begin at 1). Count backwards beginning from any given number within 20.

Tennessee

K.CC.A.2 — Count forward by ones beginning from any given number within the known sequence (instead of having to begin at 1).
1.NBT.B.3 — Know that the digits of a two-digit number represent groups of tens and ones (e.g., 39 can be represented as 39 ones, 2 tens and 19 ones, or 3 tens and 9 ones).
1.NBT.C.5 — Add a two-digit number to a one-digit number and a two-digit number to a multiple of ten (within 100). Use concrete models, drawings, strategies based on place value, properties of operations, and/or the relationship between addition and subtraction to explain the reasoning used.
K.CC.B.5.c — Recognize that each successive number name refers to a quantity that is one greater and each previous number is one less.

Texas

1.2B — use concrete and pictorial models to compose and decompose numbers up to 120 in more than one way as so many hundreds, so many tens, and so many ones;
1.3A — use concrete and pictorial models to determine the sum of a multiple of 10 and a one-digit number in problems up to 99;
1.2C — use objects, pictures, and expanded and standard forms to represent numbers up to 120;
1.5B — skip count by twos, fives, and tens to determine the total number of objects up to 120 in a set;
1.5A — recite numbers forward and backward from any given number between 1 and 120;

Utah

1.NBT.1 — Count to 120, starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral.
K.CC.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.4.c — Understand that each successive number refers to a quantity that is one greater than the previous number.
K.CC.1 — Count to 100 by ones and by tens.

Vermont

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
K.CC.A.1 — Count to 100 by ones and by tens.
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

Virginia

K.NS.1g — State the number after, without counting, when given any number between 0 and 30.
K.NS.1j — Group a collection of up to 100 objects (e.g., counters, pennies, cubes) into sets of ten and count by tens to determine the total (e.g., there are 3 groups of ten and 6 leftovers, 36 total objects).
K.NS.1a — Use one-to-one correspondence to determine how many are in a given set containing 30 or fewer concrete objects (e.g., cubes, pennies, balls), and describe the last number named as the total number of objects counted.
K.NS.1c — Represent forward counting by ones using a variety of tools, including five-frames, ten frames, and number paths (a prelude to number lines).
K.NS.2 — The student will identify, represent, and compare quantities up to 30. Students will demonstrate the following Knowledge and Skills:

Washington

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.B.2.c — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.B.2.a — 10 can be thought of as a bundle of ten ones — called a "ten."
K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.B.4.c — Understand that each successive number name refers to a quantity that is one larger.

Washington, D.C.

K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).

West Virginia

M.1.10 — Understand the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: a. 10 can be thought of as a bundle of ten ones - called a "ten." (e.g., A group of ten pennies is equivalent to a dime.) b. The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight or nine ones. c. The numbers 10, 20, 30, 40, SO, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight or nine tens (and 0 ones).
M.K.1 — Count to 100 by ones and by tens.
M.K.14 — Compose and decompose numbers from 11 to 19 into ten ones and larger two-digit numbers by using objects or drawings and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones (one ten) and one, two, three, four, five, six, seven, eight, or nine ones.
M.K.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
M.K.4 — Understand the relationship between numbers and quantities; connect counting to cardinality. a. When counting objects, say the number names in the standard order, pairing each object with one and only one number name and each number name with one and only one object. b. Understand that the last number name said tells the number of objects counted and the number of objects is the same regardless of their arrangement or the order in which they were counted. c. Understand that each successive number name refers to a quantity that is one larger.

Wisconsin

M.1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: a. 10 can be thought of as a bundle of ten ones-called a "ten." b. The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones. c. The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
M.K.CC.A.2 — Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
M.1.NBT.A.1 — Count to 120, starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral.
M.K.CC.A.1 — Count to 100 by ones and by tens.
M.1.NBT.C.4 — Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

Wyoming

1.NBT.F.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.F.2.A — 10 can be thought of as a bundle of ten ones — called a “ten”.
1.NBT.E.1 — Extend the number sequences to 120. In this range:
1.NBT.F.2.C — The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
1.NBT.G.4.A — Including adding a two-digit number and a one-digit number.