Learn the idea
Equations with a box
A box means a number we do not know yet. We can use a box in an equation to keep the two sides equal.
If 7 + □ = 10, the box must be 3 because 7 needs 3 more to make 10.
7 + □ = 10
Balance idea
Both sides of an equation must stay equal.
Look for the missing part
Use counting on, subtraction, or mental math to find the hidden number.
💡 Think aloud
Count up from the known number. Or ask, “What must the box be so both sides stay equal?”
Remember
A box is not a trick. It is just a place for the hidden number.