Activate Prior Knowledge (T manual page 57)
Review joining groups. Ask a child to hold 3 books. Then ask another child to hold 4 books. Ask the children to join their groups. Discuss with the class how they can find the sum of 3 books and 4 books.
2 Direct Instruction
Sharing Story Problems (T manual page 57A)
Materials: 6 small stuffed animals
Choose a child to act out this story using stuffed animals. There are 4 animals on the table. 2 more animals join them. How many animals are there in all? Ask children what they need to find out. (How many animals there are in all)
Then ask what numbers are in the story problem. (4,2) Help children say the addition sentence that will help them find the sum. (4+2=6)
Invite children to use the animals to act out other story problems.
For each story problem, ask: What should you do to solve the problem? (Write a number sentence.) Why is writing a number sentence helpful when you are trying to solve the problem? (It tells the number in each group and the sum.)
Student Math Book Pages – 57 & 58
Guided Practice- Complete page 57 as a whole group (use overhead or projector).
Independent Practice- Have Ss complete page 58 independently or with a partner if needed. Circulate room to provide help when needed.
3 Summarizing Strategy
Journal Idea (T manual page 58)
Have children write an addition sentence to go with this problem. “Tim has 9 baseball cards. He gets 3 more cards. How many cards does Tim have in all?” (9+3=12)
Use Test Taking Practice 2-6.
Reteaching 2-6 (R 2-6) and Practice 2-6 (P 2-6)
Optional: Enrichment 2-6 (E 2-6) or Problem Solving 2-6 (PS 2-6)
Key Standards Supported
Operations And Algebraic Thinking
Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.2
Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.
Apply properties of operations as strategies to add and subtract.3 Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)
Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false. For example, which of the following equations are true and which are false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.
Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = � – 3, 6 + 6 = �.