Reading and writing the expanded form of numbers is introduced in this unit. Students will write multidigit numbers in expanded form as singledigit multiples of powers of ten. For example 643 = 600 + 40 + 3. Students should also understand multidigit numbers written in baseten notation, recognizing that the digits in each place represent amounts of thousands, hundreds, tens, or ones (e.g., 853 = 8 hundreds + 5 tens + 3 ones).
Unitataglance
Key concept: Representing a whole number in different ways (including baseten numerals, number names, and expanded form) does not change its value. 
Key concept: Understanding the structure of the place value system allows us to determine whether one number (within 1000) is greater than, less than, or equal to another number. 
Key concept: Because 100 is greater than any quantity that can be represented by a 2digit number, we compare threedigit numbers by looking at the hundreds place first. 


Suggested pacing 
Days 14 
Days 58 
Days 912 
Suggested class plan 



Additional unit information
Prior Knowledge Needed:
 Compare two twodigit numbers; (Grade 1, Unit 13; 1.NBT.B.3)
 Understand that the three digits of a threedigit number represent the amount of hundreds, tens, and ones; (Grade 2, Unit 6; 2.NBT.A.1)
 Count to 120 starting at any number less than 120; (Grade 1, Unit 8; 1.NBT.A.1)
Units on the Horizon:
 Relating skip counting to mental addition and subtraction (Grade 2, Unit 8)
 Applying strategies to add and subtract within 1000 (Grade 2, Unit 11)
 Developing fluency in addition and subtraction (Grade 2, Unit 15)
 Developing strategies for addition and subtraction (Grade 3, Unit 3)
 Investigating patterns in number and operations (Grade 3, Unit 8)
Lessons, practice, & assessment