Topic Three: Addition Facts to 20: Use Strategies

Pacing (Duration of Unit): 10 Lessons

Desired Results

Transfer:
1. Makes sense of problems and persevere in solving them.
2. Reason abstractly and quantitatively.
3. Construct viable arguments and critique the reasoning of others.
4. Model with mathematics.
5. Use appropriate tools strategically.
6. Attend to precision.
7. Look for and make use of structure.
8. Look for and express regularity in repeated reasoning.
Established Goals:

  • 1.OA.1 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.
  • 1.OA.5 Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).
  • 1.OA.6 Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use mental 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).

Student "I Can" Statements:

  • I can understand how counting up is like adding and counting down is like subtracting.
  • I can add facts within 20.
  • I can use different strategies for addition to solve word problems (within 20).

Prerequisite Standards:
  • K.OA.1 Represent addition and subtraction with objects, fingers, mental images, drawings, sounds (e.g., claps), acting out situations, verbal explanations, expressions, or equations.
  • K.OA.2 Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using objects or drawings to represent the problem.
  • K.OA.4 Decompose numbers less than or equal to 10 into pairs in more than one way, e.g., by using objects or drawings, and record each decomposition by a drawing or equation (e.g., 5 = 2 + 3 and 5 = 4 + 1).
  • K.OA.5 Fluently add and subtract within 5.
Big Ideas:

Numbers and the Number Line
The set of real numbers is infinite and ordered. Whole numbers, integers, and fractions are real numbers. Each real number can be associated with a unique point on the number line.

Equivalence
Any number, measure, numerical expression, algebraic expression, or equation can be represented in an infinite number of ways that have the same value.

Operation Meanings & Relationships
There are multiple interpretations of addition, subtraction, multiplication, and division of rational numbers and each operation is related to other operations.

Properties
For a given set of numbers there are relationships that are always true, called properties, and these are the rules that govern arithmetic and algebra.

Basic Facts and Algorithms
There is more than one algorithm for each of the operations with rational numbers. Some strategies for basic facts and most algorithms for operations with rational numbers, both mental math and paper and pencil, use equivalence to transform calculations into simpler ones.

Practices, Processes, and Proficiencies
Mathematics content and practices can be applied to solve problems.
Essential Questions:

  • What strategies can you use for adding to 20?
Students will know...

  • To solve an addition problem by using a number line to count on.
  • To solve addition problems by counting on an open number line.
  • Doubles facts have the same number for both addends and can be used to solve problems involving real-world problems.
  • Basic addition facts that are near doubles can be found by using a related doubles fact.
  • Some addition facts can be solved by changing them to an equivalent fact with 10.
  • There are different ways to solve addition facts. Certain strategies may be easier to use for different facts.
  • Objects, drawings, and equations can help you solve different types of word problems.
  • Mathematicians use math to explain why they are right. They can talk about math that others do too.


Vocabulary:
open number line, doubles-plus-1 fact, doubles-plus-2 fact, make 10
Students will be skilled at...

  • Counting on to add using a number line.
  • Counting on to add using an open number line.
  • Fluently add doubles facts.
  • Using doubles facts to solve doubles-plus-one facts.
  • Using doubles facts to solve doubles-plus-2 facts.
  • Making 10 to add numbers to 20.
  • Solving addition problems using different strategies.
  • Solving different types of addition word problems.
  • Critiquing the reasoning of others by using known information about addition and subtraction.

Assessment Evidence

Performance Assessment:
Other Evidence:

Formative Assessments:

Learning Plan

Learning Activities:

3-1 To solve an addition problem by using a number line to count on.
3-2 To solve addition problems by counting on an open number line.
3-3 Doubles facts have the same number for both addends and can be used to solve problems involving real-world problems.
3-4 Basic addition facts that are near doubles can be found by using a related doubles fact.
3-5 Basic addition facts that are near doubles can be found by using a related doubles fact.
3-6 Some addition facts can be solved by changing them to an equivalent fact with 10.
3-7 Some addition facts can be solved by changing them to an equivalent fact with 10.
3-8 There are different ways to solve addition facts. Certain strategies may be easier to use for different facts.
3-9 Objects, drawings, and equations can help you solve different types of word problems.
3-10 Mathematicians use math to explain why they are right. They can talk about math that others do too.
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