​​Be sure to read the teacher guide prior to running the task. When you’re ready to run the task, use the tabs at the top of the page to navigate through the lesson.

Students will deepen their understanding of unitizing in two ways.

1. Counting Around: In this routine students will say the number that is ten more than the number said by the student before them. For example,

   Tomas says, “2”

   Lara says “12”

   Marta says, “22”

   Sam says, “32’’ and so on until you reach at least 132.

   For first graders count arounds should reach up to 140 so that students become more comfortable with the transition into 3 digit numbers and experience how the place value counting pattern continues into 3 digit numbers.

   Today’s Count Arounds are:  3, 13, 23, 33……133 and 6, 16, 26, 36…….136

2. Filling Boxes: When presented with baking sheets of cookies, they will figure out how many boxes of ten they can fill, how many loose cookies will be leftover and placed on the display tray, and how many cookies all together are in this batch.

Some important vocabulary to use consistently throughout the unit:

Batch: The number of cookies made at one time.  A batch of cookies is made from one or more baking sheets.

Baking sheet or sheet: Cookies are baked on sheets in random (non array) arrangements.

Boxes:  Cookies are grouped by tens in boxes. All of the cookies in the box are the same flavor. These boxes are for sale to take out of the store.

Trays: Extra cookies are kept on trays in the display case in Calvin’s shop. These single cookies are for sale in the store.

Intentionality

The purpose of the Day 2 activities is to reinforce key concepts from Day 1. Students will engage in a string of related problems through a math talk and will have an opportunity to complete independent purposeful practice. The math talk and purposeful practice serve to develop a deeper understanding of the following big ideas.

Some of the big ideas that may emerge today include:

• Unitizing (10 single cookies can be understood as 1 group of 10 cookies.)
• Place Value Number System (The two digits of a two-digit number represent amounts of tens and ones.)
• Properties of Addition [The commutative a+b=b+a and associative properties (a+b)+c=a+(b+c)]
• Equivalence [through composition and decomposition, a particular quantity can be represented in more than one way
  • (22 ones = 1 ten and 12 ones = 2 tens and 2 ones)
  • (22 cookies= 1 box and 12 loose cookies = 2 boxes and 2 loose cookies)].

Before starting this unit, students should be familiar with:

• Counting to 100 by ones and by tens.
• Writing numbers from 0 to 100. 
• Understanding the relationship between numbers and quantities; connect counting to cardinality.