In this unit, more fact strategies are developed, with a focus on strategies for solving subtraction facts. The following big ideas will be covered in this unit:
- Addition can be used to solve word problems involving situations such as “comparison”.
- Subtraction can be used to solve word problems involving situations such as “taking from”, “taking apart”, and “comparison”.
- Subtraction is a missing-addend problem.
- Unknown subtraction facts can be figured out by using known facts, such as doubles and near doubles addition facts.
- Subtraction strategy can be notated on a number line.
- Properties of addition and subtraction can be used to explain patterns in subtraction facts.
Operations & Algebraic Thinking
2.OA.A. Represent and solve problems involving addition and subtraction.
2.OA.A.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.B. Add and subtract within 20.
See standard 1.OA.6 for a list of mental strategies.
Number & Operations in Base Ten
2.NBT.A. Understand place value.
2.NBT.A.3. Read and write numbers to 1000 using base-ten numerals, number names, and expanded form.
2.NBT.B. Use place value understanding and properties of operations to add and subtract.
2.NBT.B.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.B.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.
Explanations may be supported by drawings or objects.
2.MD.B. Relate addition and subtraction to length.
2.MD.B.6. Represent whole numbers as lengths from 0 on a number line diagram with equally spaced points corresponding to the numbers 0, 1, 2, …, and represent whole-number sums and differences within 100 on a number line diagram.
2.MD.C. Work with time and money.
2.MD.C.8. Solve word problems involving dollar bills, quarters, dimes, nickels, and pennies, using $ and ¢ symbols appropriately. Example: If you have 2 dimes and 3 pennies, how many cents do you have?
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Students will have opportunities to:
- Make mathematical conjectures and arguments (MP.3)
- Make sense of others’ mathematical thinking (MP.3)
- Explain their mathematical thinking clearly and precisely (MP.6)
- Use an appropriate level of precision for their problem (MP.6)
- Use clear labels, units, and mathematical language (MP.6)
- Think about accuracy and efficiency when they count, measure, and calculate (MP.6)
- Addition can be used to solve word problems involving situations such as “adding to” and “putting together”.
- Unknown addition facts can be figured out by using known facts, such as doubles and combinations of tens.
- When you add two numbers in any order, you’ll get the same answer.
- Whole numbers can be represented as lengths on a number line diagram with equally spaced points.
- Addition strategy can be notated on a number line.
- When you add three numbers, you can pick any two numbers to add first and then add the third number. You will get the same answer.
- Addition and subtraction can be used to solve two-step word problems involving various situations.
- Known facts can be used to solve multi-digit addition and subtraction problems.
addition facts, counting back; counting up, diagonal, difference, equivalent names, fact family; related facts, friendly number, going back through 10, going up through 10, input; output, making 10, missing addend, near doubles, subtraction facts, subtraction number story, think-addition strategy, unknown, patterns, known fact, doubles, more than, less than
Bold: Listed in teacher's EDM4 edition
Normal Font: not listed in teacher’s edition as a vocabulary word but will be helpful for students in explanations
The following lesson plan sequence is obtained from Everyday Mathematics 4. Each lesson is aligned with a learning objective to inform the teachers on what students should be able to at the end of the lesson. The student objective informs the students of their learning goals for the day and it should be reviewed before, during and at the end of the lesson. Each lesson includes a mathematics task that should be implemented to meet the learning objectives. Teachers can select from the practice opportunities to reinforce the learning goals of the day.
The following language supports are for English Language Learners but could also be used to support any struggling learner in mathematics. The strategies are obtained from the SIOP model. The language objectives will support students' academic language development. The sentence stems and starters provides the support many students need to be able to participate in discussions and writing about mathematics.