Place connecting cubes in an accessible location so students can explore them before beginning Unit 2.

Display the class number line (0–130) where all students can see it and can 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:

• calculators
• connecting cubes
• number lines
• a collection of coins
• a clock with a second hand
• individual clocks
• 200 Chart (Student Guide) Reference

LESSON	SESSIONS	DESCRIPTION	SUPPLIES
LESSON 1 Addition Strategies	2	Students review mental math strategies for solving addition problems and extend their use to larger numbers. They review how to represent those strategies with manipulatives, number lines, and number sentences.	connecting cubes number lines
LESSON 2 Strategies for Making Tens	2	Students review addition facts strategies and use them to solve problems with more than two addends. Students develop mental math strategies that apply the properties of addition (e.g., using tens and making tens).	connecting cubes calculators
LESSON 3 Spinning Sums	2–3	Students spin two matching spinners to generate addition facts. They then look for patterns in sums and the addends to identify properties of addition.	spinners
LESSON 4 Magic Squares	2	Magic squares are ancient number puzzles that have intrigued people for thousands of years. Students are introduced to magic squares by reading Yu the Great: A Chinese Legend about Luo Shu, a design that appeared on the back of a turtle and revealed a magic square. Students work with other magic squares to develop problem-solving and addition skills.	calculators
LESSON 5 Subtraction Facts Strategies	2–3	This lesson begins a systematic review and practice of the subtraction facts, highlighting two subtraction strategies: using tens and thinking addition. Students practice checking subtraction problems by using addition.	spinners
LESSON 6 Spinning Differences	2	This lesson is similar to Spinning Sums. Students spin two matching spinners to generate random subtraction sentences and work in groups to look for patterns in differences.	spinners
LESSON 7 Workshop: Reasoning from Known Facts	1	Students work to improve their confidence with the using-tens and thinking-addition mental math strategies for subtraction. Students practice these strategies and practice showing their reasoning with number lines, diagrams, and number sentences. Students also apply these strategies to problems with numbers larger than ten (e.g., 45 − 7).
LESSON 8 Assessing the Subtraction Facts	1	Students do a systematic review of the subtraction facts in third grade. In this lesson, students are introduced to strategies and tools used to practice and track their progress. The subtraction facts are organized by strategy into eight groups of nine facts each. This lesson involves the first two groups of facts that can be solved with the strategies using tens and thinking addition.	envelopes