2.NBT.1 Ten $10 Make $100 2.NBT.1 Regrouping 2.NBT.1 Three Composing/decomposing Problems |
*After finishing, use Common Core Investigation
5A sessions, and DPI lessons 2.2 and 2.3.
After giving a small group time to solve a word problem, bring them back together to share their strategies. Allow a student to show their work on the board and ask the group, “How did___ know to use subtraction instead of addition to solve this problem?” This will encourage students to better make sense of the problems they solve (MP1).
As students work to solve Pinching Paperclip problems, you may notice some of them using hundreds boards, open number lines, or drawing strips and singles. At the end of the lesson, bring them back together to ask them to tell why they chose their particular tool to solve the problems. This will open dialogue about using appropriate tools strategically (MP5), while also leading to further discussion of which strategies help solve certain problems more efficiently. Watch the first video clip for MP5 for an example of this practice.
Make 100 game to practice combinations of 100. |
2.OA.1- Use addition and subtraction within 100 to solve one- and two-step 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. By the end of Grade 2, know from memory all sums of two one-digit numbers. 2.OA.3- Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counting them by 2s; write an equation to express an even number as a sum of two equal addends. 2.NBT.1- Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones; e.g., 706 equals 7 hundreds, 0 tens, and 6 ones. Understand the following as special cases: a.100 can be thought of as a bundle of ten tens — called a “hundred.” b. The numbers 100, 200, 300, 400, 500, 600, 700, 800, 900 refer to one, two, three, four, five, six, seven, eight, or nine hundreds (and 0 tens and 0 ones). 2.NBT.2-Count within 1000; skip-count by 5s, 10s, and 100s. 2.NBT.3-Read and write numbers to 1000 using base-ten numerals, number names, and expanded form. 2.NBT.5-Fluently add and subtract within 100 using strategies based on pace value, properties of operations, and /or the relationship between addition and subtraction. |
2.NBT.6-Add up to four two-digit numbers using strategies based on place value and properties of operations.
2.NBT.7-Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds. Video for clarification
2.NBT.8-Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
2.NBT.9 Explain why addition and subtraction strategies work, using place value and the properties of operations. |
Write a subtraction story problem on the board and allow students time to solve it showing their work independently. Show two different strategies for solving the problems on the board (adding up, subtracting back, etc.). Ask students to “turn and talk” and explain to a partner why each strategy works.
Ask students to think, pair, share; “How are even and odd numbers different?” Listen for students to use the words “left-overs, pairs, equal groups.”INVESTIGATION 1
Understanding what happens when you add odd and even numbers is the main focus of this Investigation. Sessions 1.1-1.4 support 2.OA.3. This is an extension of Unit 3, Investigation 3 with odd and even numbers.