Unit 2.4 Relating Addition and Subtraction to Length
Learning Objectives
Students will be able to:
• Use addition and subtraction within 100 to solve word problems involving lengths that are given in the same units, e.g., by using drawings (such as drawings of rulers) and equations with a symbol for the unknown number to represent the problem.
• Understand that equally spaced points (equidistant intervals) on the number line are iterations of unit lengths.
• Represent whole numbers as lengths from 0 on a number line diagram with equally spaced points corresponding to the numbers 0, 1, 2, . . . .
• Represent sums and differences within 100 on a number line diagram.
Essential Questions
• How would you explain how you can add using a number line?
• How would you explain how you can subtract using a number line?
• How is a number line like a ruler?
Common Core State Standards for Mathematical Content
Measurement and Data 2.MD
Relate addition and subtraction to length.
2.MD.5 Use addition and subtraction within 100 to solve word problems involving lengths that are given in the same units, e.g., by using drawings (such as drawings of rulers) and equations with a symbol for the unknown number to represent the problem.
2.MD.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.
Mathematical Practices to Be Integrated
1 Make sense of problems and persevere in solving them.
• Explain correspondences /connections between the different representations (e.g. between the number line and the equation).
• Use the number line to assist in solving problems in addition and subtraction.
• Use drawings and equations to represent and solve a problem.
Students will be able to:
• Use addition and subtraction within 100 to solve word problems involving lengths that are given in the same units, e.g., by using drawings (such as drawings of rulers) and equations with a symbol for the unknown number to represent the problem.
• Understand that equally spaced points (equidistant intervals) on the number line are iterations of unit lengths.
• Represent whole numbers as lengths from 0 on a number line diagram with equally spaced points corresponding to the numbers 0, 1, 2, . . . .
• Represent sums and differences within 100 on a number line diagram.
Essential Questions
• How would you explain how you can add using a number line?
• How would you explain how you can subtract using a number line?
• How is a number line like a ruler?
Common Core State Standards for Mathematical Content
Measurement and Data 2.MD
Relate addition and subtraction to length.
2.MD.5 Use addition and subtraction within 100 to solve word problems involving lengths that are given in the same units, e.g., by using drawings (such as drawings of rulers) and equations with a symbol for the unknown number to represent the problem.
2.MD.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.
Mathematical Practices to Be Integrated
1 Make sense of problems and persevere in solving them.
• Explain correspondences /connections between the different representations (e.g. between the number line and the equation).
• Use the number line to assist in solving problems in addition and subtraction.
• Use drawings and equations to represent and solve a problem.