Grade 1 Unit 1.2 Understanding, Representing and Solving Addition and Subtraction to 10 Key Content from This Unit: Vocabulary to Know: Addend: a number used to get the sum or total In this unit, students relate counting to addition and subtraction to add and Sum: the result of adding Difference: the result of subtracting subtract within 10 using a variety of Unknown: the part of an equation or story strategies. They solve word problems in problem to be solved, it is often more difficult for children to solve when the start is unknown that range and develop understanding (ie., Some children were on the bus. 4 got off. Now of the meaning of the equals sign (=). there are 5. How many were on the bus to begin with?) Ten-friendlies or Get-to-10s: two numbers that together make ten (ie., 4 and 6, 7 and 3) Commutative Property of Addition*: in addition, numbers may be added in any order (ie., 4 + 5 = 5 + 4) Associative Property of Addition*: in addition, no matter how the numbers are grouped, the sum will always be the same (ie., when adding 2 + 3 + 4, one might start with 3 + 4 = 7 and then solve for 2 +7 = 9 OR one might start with 2 + 3 = 5 and then solve for 5 + 4 = 9) *At this age, students need to understand the concepts of the math properties, but do not need to know the terms themselves. What came before this: Common Core Focus: In kindergarten, students solved addition word • Add and subtract within 10 to solve word problems within 10, used drawings or equations problems of various types. to decompose numbers less than or equal to 10 • Relate counting to addition and subtraction. and for any number 1–9 and found the number • Add within 10 using counting on, making that made 10. Kindergarten students were 10, and decomposing strategies. exposed to equations and the equals sign (=) • Understand the meaning of equals sign and were encouraged to write equations. (=) involving addition and subtraction. What comes after this: • Apply the commutative and associative Later this year, students apply their understanding properties as a strategy to solve addition to add and subtract within 20. Students will also problems. solve compare problems and various problem types • Represent an addition problem with with unknowns in all positions. They will also an equation using symbols to determine if equations involving addition and subtraction are true or false. represent the unknown number. 1.OA.1, 1.OA.3, 1.OA.5, 1.OA.6, 1.OA.7 Unit 1.1.2, Created Fall 2014 Spotlight on the Math Practices How Can You Help at Reason Abstractly and Quantitatively Home? Mathematically proficient students make sense of quantities • Review addition/subtraction facts to 10. and their relationships in problem situations. They recognize • Help your student notice related math real-life situations as an abstract equation or representation and facts, e.g. how does knowing the doubles represent quantities and situations symbolically. fact 6 + 6 = 12 help you solve 6 + 7? In this unit, students reason abstractly and quantitatively when they: • Have your student use an equation to • Use objects, drawings, and equations to represent represent a real-life situation. word problems. • Develop a student’s independence in • Draw a picture or tell a problem situation to asking themselves, “Can I draw represent an equation. something?”, “What can I label?”, • Draw a tape diagram or number line to help make “What do I see?”. sense of a problem situation. KEY MATHEMATICAL MODELS of the COMMON CORE Tape Diagram/Bar Model The TAPE DIAGRAM is a powerful model that students can use to solve a variety of problems. In earlier grades, tape diagrams are models of addition and subtraction, but will be used later to model multiplication, division and fractions/decimals. As students move through the grades, tape diagrams provide an essential bridge to algebra. Tape diagrams are also called “bar models” and consist of a simple bar drawing that students make to represent a word problem. Students then use the drawing to discuss and solve the problem. Below you will find several examples of tape diagrams that represent addition or subtraction situations. Note how similar the problems are, but the tape diagram can be adjusted easily to help the student visualize each problem, regardless of where the unknown is in the problem. Some Resources to Help at Home • Counting and addition practice with ten frames http://illuminations.nctm.org/Activity.aspx?id=3565 • Thinking Blocks http://www.mathplayground.com/ThinkingBlocks/thinking_blocks_modeling%20_tool.html • Some addition games at http://www.multiplication.com/games/addition-games • Free games and tools – use K and 1 activities http://www.dreambox.com/teachertools Unit 1.1.2, Created Fall 2014 .