Videos often use base-ten blocks or place value charts to show that the value of the number remains the same (e.g., changing 42 from "4 tens, 2 ones" to "3 tens, 12 ones"). 2. Key Instructional Strategies

Jumping backward on a number line to find the difference.

Subtraction with regrouping is necessary when the digit in the (top number) is smaller than the digit in the subtrahend (bottom number) within the same place value column.

Using visual "rods" (tens) and "units" (ones) to physically show the "break down" of a ten.

Breaking numbers into tens and ones (e.g., 42 becomes ) to make the subtraction of each place value clearer.

The fundamental process involves trading one ten from the tens place for ten ones .

Effective 2nd-grade videos typically employ one or more of these four primary strategies to accommodate different learning styles: