​​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 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:  4, 14, 24, 34……  and 1, 11, 21, 31…….

2. Emptying One Box at a Time: When presented with a number of boxes of 10 cookies and a number of extra cookies on a display tray, they will figure out the total number of cookies in the batch. 

When one of the boxes is opened and its cookies are added to the extra cookies, they will figure out the new number of boxes and the new number of extras cookies, and the “new” total that resulted from that action.

• For example, Calvin has 5 boxes and 3 extras. That is 53 cookies. (50+3=53)

• Then he empties one box onto the extras tray. Now he has 4 boxes and 13 extras. That is still 53 cookies. (40+13=53)

• Then he empties one box onto the extras tray. Now he has 3 boxes and 23 extras. That is still 53 cookies. (30+23=53)

• Then he empties one box onto the extras tray. Now he has 2 boxes and 33 extras. That is still 53 cookies. (20+33=53)

• Then he empties one box onto the extras tray. Now he has 1 box and 43 extras. That is still 53 cookies. (10+43=53)

• Then he empties one box onto the extras tray. Now he has 0 boxes and 53 extras. That is still 53 cookies. (0+53=53)

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. These single cookies are for sale in the store.

Intentionality

The purpose of the Day 4 activities is to reinforce key concepts from Day 3. 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.