Maryland Math 1.NOS.B.3

1.NOS.B.3 is a cluster heading. These are the individual standards under it.

• 1.NOS.B.3.a

  Compose and decompose two-digit numbers into tens and ones using objects or drawings, and equations (e.g., 10 + 4 = 14; 38 = 30 + 8).

• 1.NOS.B.3.b

  Describe a given number as the correct number of tens and ones (e.g., 14 is one ten and four ones; 38 is three tens and eight ones).

• 1.NOS.B.3.c

  Compose and decompose two-digit numbers in more than one way (e.g. 46 = 41 + 5 or 46 = 23 + 23).

01

What Students Need to Do

Students make two-digit numbers with groups of ten and single ones. They draw and write equations to show a number in more than one way.

02

What Mastery Looks Like

A student can show 34 as three tens and four ones, then trade one ten for ten ones. They can write 34 = 30 + 4 and 34 = 20 + 14 to match their drawings.

03

Common Misconceptions

Some students write 34 as 3 + 4, forgetting that the 3 means three tens. Others think 30 + 4 is the only way to split 34.

04

How to Assess It

Give students 34 straws. Ask them to show and draw two ways to group the straws, then write an equation for each way.

1. 01

   Give pairs 42 straws and rubber bands; have them bundle tens, then undo one bundle and record both arrangements.

2. 02

   Ask, “How can 27 be two tens and seven ones, but also one ten and 17 ones?” Have students draw both.

3. 03

   Play Split It: draw a two-digit number card and earn a point for each different, correct equation.

4. 04

   Show 35 pencils in three packs of ten and five loose; open one pack and ask students to describe the new groups.

• K.NOS.C.9.b

  Describe a given number as one ten and the correct number of ones (e.g., 13 is one ten and three ones).

• 2.NOS.A.1

  Use understanding of 100 as a bundle of ten tens, called a “hundred,” and compose and decompose three-digit numbers.

• K.NOS.C.9

  Understand 10 as a group, collection, or bundle of ten ones called a “ten.”