1st Grade: Number and Operations in Base Ten (1.NBT)

1st Grade Math 1st Grade: Number and Operations in Base Ten (1.NBT)

Number and Operations in Base Ten (1.NBT)

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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.

Count to 120

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Read and Write Numbers to 120

Read and Write numbers to 120

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1.NBT.B.2a

Understand 10 can be thought of as a bundle of ten ones — called a “ten.”

Understand ten as bundle of ten ones

Understand ten as a bundle of ten ones

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1.NBT.B.2b

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

Decomposing tens and ones
from 11 to 19

Decomposing tens and ones from 11 to 19

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Converting 11 to 19 to Standard or Word Form

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1.NBT.B.2c

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).

Decomposing tens and ones
from 10 to 99

Decomposing tens and ones from 10 to 99

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Converting 10 to 99 to Standard or Word Form

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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 <.

Compare Two-Digit Numbers

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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.

Add Two-Digit number by 10

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Subtract Two-Digit number by 10

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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.