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Unit 4, Lesson 23

Interpret two-digit numbers as tens and ones, including cases with more than 9 ones.

EngageNY 60 min(s)Support for English Language Learners

This lesson lays a foundation for adding like units within pairs of two-digit numbers. Students interpret numbers as different groups of tens and ones. For instance, they recognize 25 as 1 ten and 15 ones, as 2 tens and 5 ones, and as 25 ones. Working with this concept supports student understanding in the next lessons, when they will add pairs such as 14 + 16 and initially make 2 tens and 10 ones.

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Unit 4, Lesson 22

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Unit 4, Lesson 24

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2 Content Standards are aligned with this lesson

1.NBT.B.2
1.NBT.B.3

Major StandardsSupporting StandardsAdditional Standards

Standard 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:

Part of Major Cluster 1.NBT.B

1.NBT.B.2.A

10 can be thought of as a bundle of ten ones - called a "ten."

1.NBT.B.2.B

The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.

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 Math Practice Standard is aligned with this lesson

Standard MP.7

Look for and make use of structure.

Prerequisites for 1.NBT.B.2

Kindergarten

K.NBT.A.1

Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (such as 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

1st Grade

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.

Upcoming Standards for 1.NBT.B.2

1st Grade

1.NBT.B.3

Compare two two-digit numbers based on meanings of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <

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.

1.NBT.C.5

Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

1.NBT.C.6

Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), 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.

2nd Grade

2.NBT.A.1

Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones; e.g., 706 equals 7 hundreds, 0 tens, and 6 ones. Understand the following as special cases:

2.NBT.A.1.A

100 can be thought of as a bundle of ten tens - called a "hundred."

2.NBT.A.1.B

The numbers 100, 200, 300, 400, 500, 600, 700, 800, 900 refer to one, two, three, four, five, six, seven, eight, or nine hundreds (and 0 tens and 0 ones).