Before You Begin this Unit…  Unit at a Glance  
Helpful information about setting up your classroom so that it is student friendly for math learning can be found in the Implementing Investigations in Grade 2 book (Located with Teacher Manuals) on pages 10 through 14. This unit assumes that students can identify, read, write, and sequence numbers to 100, count a set of 4050 objects by ones, retell and solve simple addition and subtraction (as removal) story problems, and compose and decompose numbers up to approximately 15. If you see that students are struggling with these ideas, please refer to the “Differentiation” section for this unit. It also assumes that students are familiar with using materials, sharing ideas, and recording solutions to problems on paper. In first grade, students used addition and subtraction within 20 to solve word problems involving adding to, separating from, putting together, and taking part by using objects, drawings and equations with a symbol for the unknown number to represent the problem. In first grade, students also add and subtract within 20 and demonstrate fluency within 10. 
Suggested Dates: 27 lessons *Investigation 3: 5 lessons 

Standards Addressed in the Unit  
2.OA.1 Use addition and subtraction within 100 to solve one and twostep word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem. 2.OA.2 Fluently add and subtract within 20 using mental strategies.^{2} By end of Grade 2, know from memory all sums of two onedigit numbers. 2.NBT.5 Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction. 2.NBT.6 Add up to four twodigit numbers using strategies based on place value and properties of operations. 2.MD.7 Tell and write time from analog and digital clocks to the nearest five minutes, using a.m. and p.m. 2.MD.8 Solve word problems involving dollar bills, quarters, dimes, nickels, and pennies, using $and ¢ symbols appropriately. Link to CCSS Unpacking Document 