Move a place or make an exchange?
Distinguish a tenfold amount change from a same-value exchange.
Explore this lesson →10 practice questions · Optional read aloud · Thinking pad
Let’s understand the idea.
- Each place unit is ten times the next unit to its right.
- The same digit in adjacent places represents ten times as much on the left. Different digits need not have that value ratio.
- Multiplying a whole number by ten changes every digit's unit. Dividing by ten must not throw away a nonzero ones digit.
- An exchange changes the unit count to keep the amount fixed. Moving the same count to a different unit changes the amount when the count is nonzero.
- Zero multiplied by ten stays zero. A change beyond one million is outside this activity.
Something to notice
Ask the learner to demonstrate an exchange and a tenfold change with the same starting amount, then explain what stayed fixed in each. Compare adjacent equal digits with different digits. Look for quantity conservation during exchanges and meaningful unit changes during moves. A numerical result alone does not explain the difference.
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.