Student Actions

Teacher Actions

• Develop procedural fluency for estimating sums and differences up to 100 based on a strong sense of the base ten system while making real-world connections.

• Develop mathematical reasoning as students explain and justify estimates.

• Pose purposeful questions to assess and advance students’ reasoning and sense-making on strategies for estimating sums and differences.

• Elicit and use evidence of student thinking to support and extend learning for estimating sums and differences.

Key Understandings

Misconceptions 

• When adding and subtracting, students typically use strategies that first take into account the numbers in the tens place followed by the ones place. In turn, students and teachers should build on these strategies to estimate sums and differences up to 100.

• Relationship between numbers in terms of proximity to the next group of ten/hundred or the previous group of ten/hundred (benchmark number.)

• Estimating is important in daily life.

• Estimates require exactness.

• Rounding and estimation are the same thing 

  Knowledge Connections

Prior Knowledge

Leads to 

• Find 10 more and 10 less of a given number. (1.N.1.6)

• Use place value to compare numbers. (1.N.1.7) 

• Find 100 more and 100 less of a given number. (3.N.1.3)

• Compare numbers (3.N.1.4)

• Round numbers to thousand, ten-thousand and hundred thousand places. (3.N.1.5)