Open up a number
Write digit expansions and reconstruct their numerals.
Explore this lesson →10 practice questions · Optional read aloud · Thinking pad
Let’s understand the idea.
- Each nonzero digit contributes one represented place value to the expansion.
- You may write a value directly or as a digit times its unit. Reordering the terms does not change their sum.
- Zero terms may be omitted from an ordinary expansion. Zero places still matter when rebuilding the numeral.
- An expression with the right total may still regroup a place instead of showing the requested digit expansion.
Something to notice
Ask the learner to match every expansion term to one digit and its unit, then reconstruct the numeral. Invite another order or a digit-times-unit form and explain why it is equivalent. Look for one contribution per nonzero place. The practice checks digit expansion; broader decompositions can be explored separately.
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.