Give every digit its place
Align matching units before a written addition or subtraction.
Explore this lesson →7 practice questions · Optional read aloud · Thinking pad
Let’s understand the idea.
- Place ones with ones, tens with tens, and every other matching unit together.
- An operand with fewer digits does not move its ones place to the left.
- Internal zeros keep their places; they cannot disappear from the numeral.
- This complete chart asks for zeros in empty high places too. In a usual written layout those leading spaces may be left blank.
Something to notice
Ask the learner to name the unit of each aligned digit, especially when operands have different lengths. Try a fresh numeral with an internal zero. A completed alignment is preparation for calculation, not proof of an already fluent method.
Try it. Change it. Explain it.
Open the lesson to use its pictures and controls. In How it works, connect the picture to the idea. In Play & discover, change the quantities and notice what stays the same. In Your turn, answer questions and use the explanation to check your reasoning.
You can ask for help, draw on the thinking pad, or listen to the question and answer options. Progress distinguishes independent work from work completed with help.
Let’s try it →Curriculum connection
Grade 4 · 4.NBT · US Common Core
This lesson is mapped to these standards. A completed activity is practice evidence, not a claim of mastery. Content is checked against the linked official standards and its mathematical models are tested.