Students develop meaningful, accurate, and efficient methods for solving two-digit and three-digit addition problems. Students develop strategies to estimate sums, explore a variety of invented and mental math strategies supported with a variety of tools. Students also develop several addition methods (e.g., all-partials, expanded form, and compact) and compare and contrast them.

EXPECTATIONS
	Use this list of expectations to assess students on the key concepts and skills in this unit.
E1*	Use and apply place value concepts to make connections among representations of numbers to the thousands using base-ten pieces, number lines, expanded form, and standard form.
E2*	Represent addition problems using base-ten pieces, number lines, and number sentences.
E3	Add two-digit and three-digit numbers using mental math strategies (e.g., composing and decomposing numbers, counting on) using the 200 Chart, base-ten pieces, and number lines.
E4	Add two-digit and three-digit numbers using paper-and-pencil methods (e.g., expanded form, all-partials, compact).
E5	Estimate the number of objects in a group using benchmarks.
E6	Estimate sums using mental math strategies (e.g., rounding using benchmarks, using friendly numbers, composing and decomposing numbers, counting on).
E7*	Demonstrate fluency with the addition facts in Group E (5 + 7, 8 + 4, 8 + 5, 9 + 3, 9 + 4, 9 + 5, 10 + 1, 10 + 2, 10 + 3).
E8*	Determine the unknown number in an addition or subtraction sentence relating three whole numbers for the facts in Group E.
	* Denotes Benchmark Expectation