Montana Math MT.3.MD.6
The Standard
Measure areas by counting unit squares.
2026 Montana Mathematics Content Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students cover a shape with equal-sized unit squares and count how many fit inside. They give the area in square units.
What Mastery Looks Like
- A student can count the squares inside a rectangle or a shape with a corner missing. They can show their count and label the area in square units.
Common Misconceptions
- Some students count grid lines instead of squares. Others count only the squares around the edge or leave out squares inside an uneven shape.
How to Assess It
- Draw a 4-by-3 rectangle on grid paper. Ask students to number each square inside it and write the area in square units.
Lesson moves
Ways to Teach It
Give pairs 1-inch paper squares and a 4-by-3-inch paper rectangle to cover without gaps, then count the squares.
Show a 3-by-4 grid rectangle and ask, “Why does counting only the outside squares give the wrong area?”
Have partners draw shapes with 10 squares on grid paper, swap papers, and check each other’s counts.
Sketch a 3-by-4 tile patch on a kitchen floor plan and ask how many replacement tiles to buy.
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Printable MT.3.MD.6 Worksheet
A ready-to-print activity worksheet aligned to MT.3.MD.6, with an answer key for the teacher on its own page. No account needed.
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