Common misconceptions include thinking that only the digit at the tens place changes when adding or subtracting two multiples of 10. It's important to emphasize that the number of tens changes as there are no ones to add or subtract.
You can use visual aids such as base-10 blocks to demonstrate that when adding or subtracting two multiples of 10, only the digit at the tens place changes. Encourage students to focus on the number of tens changing, as there are no ones to add or subtract.
Students can use various strategies such as using base-10 blocks, number lines, and mental math. Base-10 blocks can help them visualize the concept, while number lines provide a sequential representation. Mental math strategies involve recognizing patterns and applying addition or subtraction rules.