Common Core Standards: Mathematical Concepts Your Child Should Learn in Grade 2
In Grade 2, for Common Core Standards, students begin to build a conceptual foundation for multiplication as they think about combining groups when adding. Students continue to encounter more complex concepts; build on their previous understanding of place value; and increase the precision of measurements with time, money, and objects by using standard units of measure.
Common Core Standards in Grade 2 focus on four areas:

Addition and subtraction in preparation for multiplication: An emphasis on adding and subtracting equal groups of numbers prepares students to multiply groups of objects in later grades.

Use of the base ten number system in addition and subtraction: Students extend their use of base ten when adding and subtracting numbers up to 1,000.

Using standard units of measure: Students use centimeters, inches, seconds, minutes, and other standard units of measure to take measurements.

Describing and analyzing shapes: Students learn to use the sides and angles of shapes to compare and contrast them to other shapes. This helps them understand attributes of shapes, such as area and volume, that are used in later grades.
Operations and algebraic thinking
In Grade 2, students work toward gaining fluency in adding and subtracting numbers from 1 to 20 and solving addition and subtraction word problems with numbers from 1 to 100. Some problems may require multiple steps. Finding the total number of items by combining equal groups provides a basis for multiplication in later grades.
Help your child prepare for multiplication by working with equal groups of objects. For example, put three groups of two pieces of cereal on the table. Ask her to say how many groups there are and how many objects are in each group. Then ask her to count the total. She will see that three groups of two equal six.
Recognizing the combination of equal groups is important in strengthening her conceptual foundation for understanding multiplication. If this is too difficult at first, let your child practice skip counting by twos, threes, and fives to further support her understanding of combining equal groups of numbers.
Number and operations in base ten
Place value extends to include the hundreds place, and students practice counting by fives, tens, and hundreds. Students are also able to write numbers up to 1,000 using numerals, names of numbers, and expanded forms (for example, writing 1,727 as 1,000 + 700 + 20 + 7). Students are also expected to add and subtract in their heads using tens and hundreds.
Practice counting using fives, tens, and hundreds, backward and forward. This is a simple way to build fluency in counting and reinforce skills in addition and subtraction. Writing some of these numbers in expanded form also supports the understanding of place value. You can also ask your child questions like “How many tens are there in 215?” to see if she can identify that there are 21 tens.
Measurement and data
Use of specific units, such as centimeters and inches, requires students to be precise with measurements. Students begin to apply previously acquired skills in addition and subtraction to measurements. They also practice telling time to the nearest fiveminute increment, using money and related symbols to solve word problems, and using graphs to represent collected data.
Have your child measure objects around the house using different units of measurement, such as inches, feet, centimeters, and meters. Remember to make him be specific! Ask your child to measure something in sections and add the measurements. Periodically ask your child to tell you the time to the nearest fiveminute increment.
Geometry
The use of shapes becomes more complex, and students are expected to recognize specific characteristics of geometric shapes, such as the concept that a triangle has three sides and three angles and a cube has six equal faces. Students continue to divide shapes into multiple equal parts, including halves, thirds, and fourths.
Ask your child to recognize different shapes, including triangles, rectangles, cubes, pentagons, and hexagons, and to describe their characteristics. Practice drawing shapes and having your child divide them into equal parts. Be sure to let her work with a variety of shapes and make her verbalize the parts into which she is dividing shapes (halves, third, or fourths).