What was used?
Find an unknown removed amount from start and remainder.
Explore this lesson →8 practice questions · Optional read aloud · Thinking pad
Let’s understand the idea.
- Identify the starting amount and the amount still present.
- The unknown removed part and remainder together equal the start.
- Record the quantity that the question asks for, with its unit.
Something to notice
Ask the learner to connect the unknown card to the part used, rather than automatically putting it on the result side.
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.NF · 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.