Montana Math MT.2.OA.1
The Standard
Use addition and subtraction within 100 to solve one- and two-step problems in context involving all problem types. This standard should incorporate cultural context relating to Montana Indigenous Peoples and local communities.
2026 Montana Mathematics Content Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students solve one-step and two-step stories using addition and subtraction within 100. They find missing starts, changes, totals, parts, and comparison amounts, then show their thinking with drawings or equations.
What Mastery Looks Like
- A student chooses an operation based on the story, even when the missing number comes first. They solve both steps when needed and check whether their answer makes sense.
Common Misconceptions
- Students may add whenever they see “more,” even when they need to find the smaller amount. They may assume the missing number always comes at the end, or stop after the first step.
How to Assess It
- Exit ticket: “A library had some books. It received 18 more and lent out 9. Now it has 34. How many did it start with?” Ask for a drawing and two equations.
Lesson moves
Ways to Teach It
Give pairs 50 counters and a start, change, end mat; have them model 23 books, add 14, remove 8, and record two equations.
Ask partners: “Library A has 46 books, 18 more than Library B; how many books does B have, and why?”
Play Missing Number Match: partners draw cards showing equations such as ___ + 17 = 42, invent matching stories, then trade to solve.
Use a public Crow Fair flyer; invent a visitor-group problem with 24 arriving, 18 joining, and 15 leaving, then solve it.
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Printable MT.2.OA.1 Worksheet
A ready-to-print activity worksheet aligned to MT.2.OA.1, with an answer key for the teacher on its own page. No account needed.
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