Montana Math MT.1.OA.2
The Standard
Solve problems in context that call for addition of three whole numbers with a sum less than or equal to 20 in context of all 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 stories that have three amounts to add, with a total of 20 or less. They show the amounts with objects, drawings, or numbers and explain what the total means.
What Mastery Looks Like
- A student can add all three amounts, even when they appear in different parts of the story. They can write an equation and answer with a label, such as 13 books.
Common Misconceptions
- Some students add only two amounts or count one group twice. Others see three groups and add 3 instead of adding the number in each group.
How to Assess It
- Exit ticket: “At a community meal, 4 volunteers set tables, 6 other volunteers serve food, and 3 more clean up. How many volunteers help? Draw a model and write an equation.”
Lesson moves
Ways to Teach It
Give pairs 20 counters and three paper cups; put 4, 6, and 3 counters in the cups, then combine them and count.
Ask, “Would you add 4, 6, or 3 first in the volunteer story, and why?” Have partners compare their choices.
Have students roll three dice, write a story using the three numbers, and trade stories with a partner to solve.
Show a photo from a Montana tribal library’s public website; students invent three small book stacks and find the total, up to 20.
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Printable MT.1.OA.2 Worksheet
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