Identify and gather a few student coats, jackets, or sweaters for use in Lesson 2.

Find a place to display a large monthly calendar for students to see and write on. As a daily routine, students will record their thinking on this calendar as they explore patterns in factors and multiples. See Unit 3 Lesson 5.

Display the class number line (0–130) where students can see and reach it with a pointer.

Attach a desk number line (0–100) to each student's desk to use throughout the year.

Display the Math Practices page where all students can see it.

Have the following tools readily available for the Daily Practice and Problems items in this unit:

• coins
• counters or connecting cubes
• metersticks
• number lines
• base-ten pieces
• monthly calendar
• calculators
• individual clocks
• 200 Chart (Student Guide) Reference
• Addition Strategies Menu (Student Guide) Reference
• Subtraction Flash Cards: All Groups (stored in an envelope)
• Subtraction Facts I Know chart (from Lesson 1)

LESSON	SESSIONS	DESCRIPTION	SUPPLIES
LESSON 1 500 Hats	2	The 500 Hats of Bartholomew Cubbins by Dr. Seuss provides a context for the continued development of students' own addition strategies with multidigit numbers. Students partition, add, and subtract two- and three-digit numbers using mental math strategies. They use number lines and expanded form to help visualize the partitions and operations.	number lines
LESSON 2 The Coat of Many Bits	3	Students trace an outline of their coats or jackets onto a large sheet of paper and measure the area inside the outline. The data collected through these measurements tend to be “big” (i.e., four-digit) numbers, that are then used in problem situations. After working with these large numbers, students examine place value in the base-ten number system.	coats large sheet of paper crayons index cards scissors tape set of base-ten pieces
LESSON 3 Close Enough!	3	Students use base-ten pieces and number lines to develop an understanding of rounding numbers to the nearest ten and hundred. They then estimate sums using strategies including rounding to benchmarks, using convenient numbers, and front end estimation to solve problems involving estimation of sums.	base-ten pieces number lines tape
LESSON 4 Addition Review	2–3	Students explore addition using their knowledge of place value. They add two-digit numbers using mental math strategies and paper-and-pencil methods (all-partials and compact). The lesson concentrates on understanding paper-and-pencil methods by making connections to base-ten pieces. This review prepares students for extending these concepts and skills to larger numbers in Lesson 5.	base-ten pieces
LESSON 5 Addition with Larger Numbers	4	Students solve three- and four-digit addition problems. They begin by modeling addition with base-ten pieces. They then use paper-and-pencil methods, including both an all-partials algorithm and the compact algorithm. Students play the Digits Game for further computation practice and development of place value concepts.	base-ten pieces scissors envelope
LESSON 6 Workshop: Addition	2–3	This Workshop allows students to choose from several problem sets to continue to develop and practice their strategies for solving multidigit addition problems. Students also identify patterns in the different types of palindromes while practicing multidigit addition.	crayons or colored pencils set of base-ten pieces calculator