Montana Math MT.1.OA.3
The Standard
Flexibly compose and decompose numbers to add and subtract.
2026 Montana Mathematics Content Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students break numbers into useful parts to add and subtract. They use counters, drawings, or equations to show that the parts still make the same amount.
What Mastery Looks Like
- For 8 + 5, a student splits 5 into 2 and 3, then adds 8 + 2 + 3 to get 13. For 13 - 5, they subtract 3 to reach 10, then 2 more to get 8.
Common Misconceptions
- Students may split 5 into 2 and 2, losing one. Some change 8 + 5 to 10 + 5 without taking 2 from the 5. Others stop at 10 when subtracting 5 from 13.
How to Assess It
- Exit ticket: Show how breaking apart 5 helps you solve both 8 + 5 and 13 - 5. Write the parts you used.
Lesson moves
Ways to Teach It
Give pairs 13 counters and a ten-frame; have them build 8 + 5 by moving two counters to fill the frame.
Ask, “How can splitting 5 into 2 and 3 help you solve both 8 + 5 and 13 - 5?”
Play Make Ten Match: students pair cards like 9 + 4 and 9 + 1 + 3, then check with counters.
Give a pretend shopper 8 pennies and 5 pennies; ask how to make a group of 10 before counting the total.
Free download
Printable MT.1.OA.3 Worksheet
A ready-to-print activity worksheet aligned to MT.1.OA.3, with an answer key for the teacher on its own page. No account needed.
PDF, US Letter, prints cleanly in black and white.
Download the worksheetKeep exploring
Related Standards
- MT.K.OA.5
Flexibly and accurately add and subtract within 5.
- MT.1.OA.6
Flexibly, accurately, and efficiently add and subtract within 10.
- MT.K.NBT.1
Compose and decompose numbers from 11-19 into ten ones and further ones in multiple ways and record each composition or decomposition by a drawing or an equatio...
Turn this exact standard into a lesson
Grade, subject, topic, and the complete standard are prefilled. Create one free, no account needed.
Also for this standard:Make a WorksheetMake a QuizMake a Sub Lesson