Unit 5

Numbers 10 – 20 and Counting to 100






Description: Students explore numbers 10-20.  They apply their skill with and understanding of numbers within 10 to teen numbers, which are decomposed as 10 ones and some ones.  For example, 12 is 2 more than 10.  The number 10 is special and is the anchor that will eventually become the “ten” unit in the place value system if future grades.




Counting and Cardinality



Count to 100 by ones and by tens.



Count forward beginning from a given number within the known sequence (instead of having to begin at 1).




Write numbers from 0 – 20.  Represent a number of objects with a written numeral 0 – 20 (with 0 representing a count of no objects).




Understand the relationship between numbers and quantities; connect counting to cardinality.

a. When counting objects in standard order, say the number names as they relate to each object in the group, demonstrating one-to-one correspondence.

b. Understand that the last number name said tells the number of objects counted. The number of objects is the same regardless of their arrangement or the order in which they were counted.

c. Understand that each successive number name refers to a quantity that is one larger.

K.CC. 5


K.CC.5: Count to answer “How many?” questions.

a. Count objects up to 20, arranged in a line, a rectangular array, or a circle.

b. Count objects up to 10 in a scattered configuration.

c. When given a number from 1-20, count out that many object.

Numbers and Operations in Base Ten




Gain understanding of place value.

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

b. Compose and decompose numbers 11 to 19 using place value (e.g., by using objects or drawings).c. Record each composition or decomposition using a drawing or equation (e.g., 18 is one ten and eight ones, 18 = 1 ten + 8 ones, 18 = 10 + 8).





Enduring Understandings:


·         Students will count to 100 by ones and tens. They will count objects to 20 and represent that number of objects with a written numeral from 1-20.

·         Students will use comparative vocabulary to describe items in two sets between 1–20. 

·         Students will compare two objects with a measurable attribute in common to see which object has more of/less of the attribute and describe the difference. They will be introduced to solving addition and subtraction word problems and to adding and subtracting within 10 using objects fingers and/or drawings.

·         Students will decompose numbers up to 20 into partners in multiple ways (e.g. 12 = 10 + 2 and 12 = 7 + 5). They will begin to find a number that makes 20 when given any number from 1 – 19.

·         Students will gain an understanding of place value by composing and decomposing teen numbers in addition sentences.

·          Students will record each composition or decomposition using a drawing or equation (e.g., 18 is one ten and eight ones, 18 = 1 ten + 8 ones, 18 = 10 + 8).



       Essential Questions:


  • What is base ten and how can it be used?
  • What are different ways to represent a number?
  • How do we count? Why do we count?
  • Is there more than one way to count?
  • Why is it important for me to think in numbers?
  • How do I show my thinking in different ways?
  • How can I compare numbers?
  • How can I use concrete objects to add and subtract in a story problem?