Unit 4

Numbers to 99

Unit Goals

Unit Narrative

This unit develops students’ understanding of the structure of numbers in base ten, allowing them to see that the two digits of a two-digit number represent how many tens and ones there are.

In a previous unit, students counted forward by one and ten within 100 in the Choral Count routine. They learned that 10 ones make a unit called a “ten” and that a “teen number” is a ten and some ones.

As students count and group quantities, they generalize the structure of two-digit numbers in terms of the...

Section A

Section Goals

Section Narrative

In an earlier unit, students used a 10-frame to represent a unit of ten. In this section, they make sense of other representations of units of ten—towers of 10 connecting cubes, base-ten drawings, words, and numbers—to build their understanding of the base-ten system.

Students count collections with a multiple of 10 objects in each. As they represent the quantity in...

Let’s count objects.

Let’s match different representations of numbers.

Let’s add and subtract 10.

Let’s add and subtract tens.

Let’s add and subtract.

Section A Practice Problems

to access Section Checkpoints.

Section A

Let’s count objects.

Let’s match different representations of numbers.

Let’s add and subtract 10.

Let’s add and subtract tens.

Let’s add and subtract.

Section B

Section Goals

Section Narrative

In this section, students learn that the two digits in a two-digit number represent amounts of tens and ones. They count collections of objects that don’t contain a multiple of 10 and express the quantity in a way that makes sense to them. Their understanding of teen numbers helps them see the collections in terms of tens and ones.

Students...

Let’s organize, count, and show collections.

Let’s learn more about tens and ones.

Let’s think about how 2-digit numbers can be shown.

Let’s show numbers in different ways.

Let’s write 2-digit numbers.

Let’s add tens to 2-digit numbers.

Let’s add and subtract tens in our heads.

Let’s add and subtract and work with tens and ones.

Section B Practice Problems

to access Section Checkpoints.

Section B

Let’s organize, count, and show collections.

Let’s learn more about tens and ones.

Let’s think about how 2-digit numbers can be shown.

Let’s show numbers in different ways.

Let’s write 2-digit numbers.

Let’s add tens to 2-digit numbers.

Let’s add and subtract tens in our heads.

Let’s add and subtract and work with tens and ones.

Section C

Section Goals

Section Narrative

In this section, students use their understanding of the base-ten structure to compare and order numbers to 99. Students notice that if a two-digit number has more tens it will be greater than a number with fewer tens, no matter how many ones there are. This is true because we know the value of the digit in the ones place...

Let’s compare numbers.

Let’s make sense of comparisons and decide if they're true.

Let’s use symbols to write comparisons.

Let’s compare and order numbers.

Let’s play games about tens and ones.

Section C Practice Problems

to access Section Checkpoints.

Section C

Let’s compare numbers.

Let’s make sense of comparisons and decide if they're true.

Let’s use symbols to write comparisons.

Let’s compare and order numbers.

Let’s play games about tens and ones.

Section D

Section Goals

Section Narrative

In this section, students deepen their understanding of the base-ten structure by representing two-digit numbers with different amounts of tens and ones. They also extend their comparison work by comparing numbers expressed in different ways.

Students begin by making a number with towers of 10 and singles, using more than 9 single cubes. This prompts students to consider how to...

Let’s make 2-digit numbers with tens and ones in different ways.

Let’s make 2-digit numbers in different ways.

Let’s compare numbers.

Let’s play games about tens and ones.

Let's estimate how many objects are in a group.

Section D Practice Problems

to access Section Checkpoints.

Section D

Let’s make 2-digit numbers with tens and ones in different ways.

Let’s make 2-digit numbers in different ways.

Let’s compare numbers.

Let’s play games about tens and ones.

Let's estimate how many objects are in a group.

to access End-of-Unit Assessments.

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Numbers to 99

Unit Goals

Unit Narrative

Section Goals

Section Narrative

Section A Practice Problems

Section Goals

Section Narrative

Section B Practice Problems

Section Goals

Section Narrative

Section C Practice Problems

Section Goals

Section Narrative

Section D Practice Problems

Unit 4 Resources

About Unit 4

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Section Goals

Section Narrative

Section B Practice Problems

Section Goals

Section Narrative

Section D Practice Problems

Section Goals

Section Narrative

Section C Practice Problems

Section Goals

Section Narrative

Section A Practice Problems