In second grade math, one of the concepts that students learn is called "expanded form." This is a useful tool for understanding the value of multi-digit numbers. Expanded form breaks a number down into its individual place values, showing how much each digit contributes to the overall value of the number. For example, the number 123 can be broken down into 100 + 20 + 3 in expanded form.

By learning expanded form, students can also practice their place value skills. They can identify the value of each digit in a number and compare numbers by looking at their expanded forms. This skill will come in handy as they progress to more advanced math concepts in future grades.

Overall, expanded form is an important concept for second graders to master in order to build a strong foundation in math. With practice, students can become confident in their ability to work with multi-digit numbers and understand their value.