Students organize data to make counting and comparing easier, and advance to apply counting as a strategy for addition. Students compare equivalent ways to make the same total and reason for the meaning of the equal sign.

Students use word problems to help notice relationships between addition and subtraction. Students are introduced to change unknown and comparison problem types, and they explore ways of finding an unknown part for the first time.

Students use the unit of ten to make easier problems by decomposing addends and grouping them in any order. They intuitively apply the associative and commutative properties and then learn how they can use strategies such as counting on, making ten, taking from ten, subtracting to get to a ten, and relating operations to break down larger addition and subtraction problems. 

Students explore units within the context of measurement. After comparing lengths indirectly, students iterate length units, such as centimeter cubes and 10-centimeter sticks, to describe and compare lengths.

Students will develop an understanding of the base ten system. They continue to advance their use of tens and ones as they compose and compare numbers. Students then make easier problems to add and subtract within 100.

Students reason about shapes and their attributes. They compose and decompose shapes, building an understanding of part–whole relationships, including fractions. Students advance place value understanding through 120, add within 100, and solve more complex word problem types.