Lesson objective: Students extend their understanding of counting to 20. Given a number 120, students will accurately count out that many objects, and write the corresponding numeral. Students understand that they can count the same quantity in different arrangements: in a circle, in a line or in a rectangular array. Students develop a system for ensuring they have counted each object and for keeping track of the objects that have already been counted.
This lesson provides an opportunity for students to apply their knowledge and understanding of quantity to a mathematical situation. Students are asked to choose a number (120) and write the number on their story mat. They accurately count out that many objects and choose how they will represent it: arranging in a circle, putting them in a line or arranging them in a rectangular array such as a tens frame. Students may want to show their number in more than one way.
Key Concept students will use:
 The number of objects arranged in a line, rectangular array, or circle is the same no matter how it is counted.
 Given a number 120 we can count out that number of objects.
Skills students will use:

Each item in a collection must be counted once and only once; (Unit 1; K.CC.B.4a)

Count up to 10 objects accurately; (Grade K, Unit 2; K.CC.B.4a)
 Any number of objects can be represented with a written numeral; (Grade K, Unit

2, KK.CC.A.3)

Count to answer “how many?” questions about things arranged in a line; (Grade K, Unit 2, K.CC.B.5)

Count to answer “how many?” questions about things arranged in a line or rectangular array; (Grade K, Unit 3, K.CC.B.5)
Students engage in Mathematical Practice 2 (Reason abstractly and quantitatively) as they connect concrete representations to written numerals. They also engage in Mathematical Practice 6 (Attend to Precision) as they develop strategies for counting accurately and efficiently.
Key vocabulary:
 circle
 ten frames
 line
 rectangular array
 value
Special materials needed:
 120 number path
 countable objects
 story mat (ten frames and paper to record work may also be used)