Know how to add three whole numbers whose sum is less than or equal to 20. I can solve addition problems using the draw a picture strategy. I can add three addends. To further students’ understanding of the concept of addition, students create word problems with three addends. They can also increase their estimation skills by creating problems in which the sum is less than 5, 10 or 20. They use properties of operations and different strategies to find the sum of three whole numbers such as: Counting on and counting on again (e.g., to add 3 + 2 + 4 a student writes 3 + 2 + 4 = ? and thinks, “3, 4, 5, that’s 2 more, 6, 7, 8, 9 that’s 4 more so 3 + 2 + 4 = 9.” Making tens (e.g., 4 + 8 + 6 = 4 + 6 + 8 = 10 + 8 = 18) Using “plus 10, minus 1” to add 9 (e.g., 3 + 9 + 6 A student thinks, “9 is close to 10 so I am going to add 10 plus 3 plus 6 which gives me 19. Since I added 1 too many, I need to take 1 away so the answer is 18.) Decomposing numbers between 10 and 20 into 1 ten plus some ones to facilitate adding the ones Using doubles Using near doubles (e.g.,5 + 6 + 3 = 5 + 5 + 1 + 3 = 10 + 4 =14) Students may use document cameras to display combining strategies. This gives them the opportunity to communicate and justify their thinking. Reasoning Target Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20 Performance Target
rewrite true/false statements using the symbols, < and >. Examples of true and statements: 7 = 8 – 1 8 = 8 1 + 1 + 3 =7 4 + 3 = 3 + 4 6 – 1 = 1 – 6 12 + 2 – 2 = 12 9 + 3 = 10 5 + 3 = 10 – 2 3 + 4 + 5 = 3 + 5 + 4 3 + 4 + 5 = 7 + 5 13 = 10 + 4 10 + 9 + 1 = 19 Students can use a clicker (electronic response system) or interactive whiteboard to display their responses to the equations. This gives them the opportunity to communicate and justify their thinking. Make sense of problems and preserver in solving them. Reason abstractly and quantitatively Construct viable arguments and critiques the reasoning of others Model with mathematics Use appropriate tools strategically Attend to precision Look for and make use of structure Look for and express regularity in repeated reasoning Cluster: Work with addition and subtraction equations.
Vocabulary 1 Topic 2 3 4 Topic 5 6 In all Inside Outside part double plus (+) add sum addition sentence equals (=) join order addend Missing part Subtract Difference Subtraction sentence Minus sign Equal sign Take away Compare Same amount Near double 2 less than 1 less than 0 less than Doubles Doubles plus 1 Doubles plus 2 Related facts Fact family
Compare3 (“How many more?” version): Lucy has two apples. Julie has five apples. How many more apples does Julie have than Lucy? (“How many fewer?” version): Lucy has two apples. has five apples. How many fewer apples does Lucy have than Julie? 2 + ? = 5, 5 – 2 = ? (Version with “more”): Julie has three more apples than Lucy. Lucy has two apples. How many apples does Julie have? (Version with “fewer”): Lucy has 3 fewer apples than Julie. Lucy has two apples. How many apples does Julie have? 2 + 3 = ?, 3 + 2 = ? (Version with “more”): has three more apples than Lucy. Julie has five apples. How many apples does Lucy have? (Version with Lucy has 3 fewer apples than Julie. Julie has five apples. How many apples does Lucy have? 5 – 3 = ?, ? + 3 = 5