Build the sum, carry its meaning
Use a written addition method while accounting for each composed unit.
Explore this lesson →10 practice questions · Optional read aloud · Thinking pad
Let’s understand the idea.
- Start with the original addends aligned by place value.
- A column combines both digits and any unit carried from the next smaller place.
- Ten units compose into one of the next larger unit. Record the remaining digit and account for the composed unit.
- The little carried 1 represents a receiving-place unit. Record 0 in this chart when no carry leaves a column.
- Check the complete sum with subtraction. A different visual position for a carry mark can still represent the same method.
Something to notice
Ask what a carried mark is worth in the receiving place. Trace a carry through several columns and include a sum with internal result zeros. Observe a fresh written calculation as well as the supplied chart; the chart's semantic fields do not require one particular handwriting layout.
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.